
^{12}C (1990AJ01)(See Energy Level Diagrams for ^{12}C) GENERAL: See also (1985AJ01), 2 [Electromagnetic Transitions in A = 1112] (in PDF or PS), 12.6 [Table of Energy Levels] (in PDF or PS) and 12.7 [The decay of some ^{12}C levels] (in PDF or PS). Shell model: (1984CA1N, 1984ZW1A, 1985AN16, 1985AR07, 1985CA23, 1985KO2B, 1985MI23, 1986YO1F, 1987GU1C, 1987JI01, 1987KI1C, 1987PR01, 1987SC1J, 1988GU13, 1988JA13, 1988OR1C, 1988WO04, 1989KW1A). Deformed Models: (1984LO05, 1984SA37, 1985RO1G, 1986KU1P, 1986LE16, 1987HO1C, 1987PR03, 1988KH07). Cluster Model: (1983DZ1A, 1983JA09, 1984KR10, 1985DE05, 1985KO2B, 1985KW02, 1986GU1F, 1986KA51, 1986OR1C, 1986SA03, 1986SA1D, 1986SU12, 1986ZE1A, 1987JI01, 1987KU1B, 1987MI1L, 1987WA07, 1987ZE05, 1988FL1A, 1988HA39, 1988KA1Z, 1988MI26, 1988OS04, 1988OS1E, 1988RU1C, 1989KW1A, 1989OR05). Special states: (1984BA38, 1984CA1N, 1984CO16, 1984CO21, 1984MO13, 1984SA31, 1984SA37, 1984TR1C, 1984ZW1A, 1985CA23, 1985CH27, 1985CO05, 1985GO1A, 1985HA1J, 1985KU22, 1985PA12, 1985RO1G, 1985SHZL, 1986AN10, 1986CH25, 1986DI04, 1986HU1E, 1986KA51, 1986KH1G, 1986OR1C, 1986PA06, 1986SA03, 1986SA32, 1986SU18, 1986VO07, 1987BL18, 1987BO1L, 1987CA1E, 1987JI01, 1987KA18, 1987KI1C, 1987MA08, 1987PR01, 1987PR03, 1987SC1J, 1988AJ1C, 1988AL1D, 1988BL10, 1988GU13, 1988KW02, 1988PO1C, 1988SP1A, 1989BA60, 1989KW1A, 1989OR02, 1989OR05, 1989RO03). Electromagnetic transactions: (1984CI1B, 1984ER06, 1984LO05, 1984MO13, 1984VA06, 1985AR07, 1985CA23, 1985GR1A, 1986AN10, 1986CH25, 1986KE1P, 1986SA32, 1986VO07, 1987CA1E, 1987ER1F, 1987RA01, 1987ST1E, 1989BA60). Giant resonances: (1984BA38, 1984RA1H, 1985GI1G, 1985GO1A, 1985OR1F, 1986ER1A, 1986NA1H, 1987FE05, 1987GOZK, 1987KI1C, 1987MI1L, 1988CO1G, 1988HO10, 1988MI26, 1989LH02). Astrophysical questions: (1982BA1D, 1982BU1A, 1982CA1A, 1982GR1A, 1982WO1A, 1984CO1H, 1984HA1R, 1984LA1J, 1984LI1L, 1984RA1E, 1984TR1C, 1984WE1C, 1985AR1A, 1985BR1E, 1985DW1A, 1985GU1A, 1985HA1R, 1985HE1F, 1985KH1D, 1985KO2A, 1985MI1E, 1985NO1B, 1985TA1A, 1985YO1A, 1986CH1H, 1986CO1R, 1986DO1L, 1986GO1Q, 1986KH1G, 1986LA16, 1986LA1C, 1986MA1E, 1986MA2E, 1986SM1A, 1986SN1C, 1986SN1D, 1986TH1E, 1986TR1C, 1986WI1L, 1986WO1A, 1987AL1B, 1987AR1C, 1987AU1A, 1987BE1H, 1987BO1B, 1987BR1P, 1987CU1A, 1987DO1A, 1987DW1A, 1987FU04, 1987HA1C, 1987HA1U, 1987HA1E, 1987KR1M, 1987LA1C, 1987MA2C, 1987ME1B, 1987MU1B, 1987PI1E, 1987PR1A, 1987RA1D, 1987RI1B, 1987SA1D, 1987SO1F, 1987WA1L, 1987WA1F, 1988AP1A, 1988AR1H, 1988AS1D, 1988BA86, 1988CA26, 1988CO1D, 1988CR1A, 1988CUZX, 1988DE1I, 1988DU1G, 1988FE1A, 1988FO1E, 1988JU1C, 1988KA1G, 1988MI1A, 1988PA1H, 1988RE1F, 1988SC1A, 1988TR1H, 1989BO1M, 1989CU1F, 1989DE1J, 1989GU1Q, 1989HA1O, 1989JI1A, 1989KA1K, 1989ME1C, 1989NO1A, 1989TH1C, 1989WE1G, 1989WY1A). Applications: (1984CA1D, 1984HO1E, 1986BR1Q, 1986DR1E, 1986EN1A, 1986FR1H, 1986HE1F, 1986KI1J, 1986KO2E, 1986KR1F, 1986PE1F, 1986ST1K, 1986WE1E, 1987NA1D, 1987ST1C, 1988AL1K, 1988BU1C, 1988GO1M, 1988ILZZ, 1988MA1I, 1988PU1A, 1988RO1L, 1988SC1C, 1989BO1L). Complex reactions involving ^{12}C: (1983AG1A, 1983AL1G, 1983AL1H, 1983BO1D, 1983EL1A, 1984AB1C, 1984AI1B, 1984AN1G, 1984BA2F, 1984CH1L, 1984DE1Q, 1984FI17, 1984GA1G, 1984HO23, 1984KA1J, 1984KA1L, 1984KO1P, 1984MA1P, 1984NA12, 1985PA08, 1984ST1B, 1984XI1B, 1985AB1F, 1985AG1A, 1985BA1V, 1985FA02, 1985GA1H, 1985GH1A, 1985GU1A, 1985HA1N, 1985JA18, 1985KA1E, 1985KA1G, 1985KAZQ, 1985KI1E, 1985KW03, 1985LI1B, 1985MC03, 1985MO02, 1985MO08, 1985NE1G, 1985PO11, 1985PO14, 1985SI15, 1985SI19, 1985ST1B, 1985TA18, 1985UT01, 1985WA22, 1986AB06, 1986AL25, 1986AV1A, 1986BA1E, 1986BA1Q, 1986BE2M, 1986BO1R, 1986BO1B, 1986BU1K, 1986CH2G, 1986CS1A, 1986GH1A, 1986GR1L, 1986GR08, 1986GR1A, 1986GR1B, 1986GU1F, 1986HA1B, 1986KI1C, 1986MA19, 1986ME06, 1986MO15, 1986PL02, 1986PO06, 1986RA1L, 1986RE13, 1986SA30, 1986SH25, 1986SH1F, 1986SO10, 1986ST13, 1986UT01, 1986VA10, 1986VA18, 1986VA23, 1986WA1H, 1986WE1C, 1987AK1A, 1987AN1C, 1987AR19, 1987BA02, 1987BA1I, 1987BA31, 1987BA38, 1987BA1T, 1987BE58, 1987BE55, 1987BO23, 1987BO1K, 1987BU07, 1987CH1L, 1987DE37, 1987DO13, 1987FA09, 1987FE1A, 1987GE1A, 1987GH1A, 1987GO17, 1987GR1O, 1987JA06, 1987KI05, 1987KO15, 1987KW02, 1987LY04, 1987MU03, 1987MU1D, 1987NA01, 1987PA01, 1987PA1D, 1987PO23, 1987RI03, 1987RO10, 1987SH23, 1987SI10, 1987SN01, 1987SO15, 1987ST01, 1987TAZU, 1987VI02, 1987VI14, 1987YA16, 1987YI1A, 1988AV03, 1988AY03, 1988BA28, 1988BO1O, 1988BR1N, 1988CA06, 1988CA27, 1988CE01, 1988DE1J, 1988EL1D, 1988FE1A, 1988GA11, 1988GA12, 1988GA31, 1988GH1A, 1988GO1F, 1988GO11, 1988GU1K, 1988HA03, 1988KH1B, 1988KH1H, 1988KHZX, 1988KI06, 1988KW1C, 1988LI1H, 1988MI28, 1988MO1K, 1988MU1E, 1988PAZS, 1988POZZ, 1988PO1F, 1988PR1C, 1988RE13, 1988RU01, 1988SA19, 1988SH03, 1988SH1H, 1988SI01, 1988SM07, 1988TE03, 1988TS03, 1988TS01, 1988UC01, 1988UT02, 1989BL1D, 1989BR35, 1989CEZZ, 1989CH28, 1989CI1C, 1989FI05, 1989GH1B, 1989GU1C, 1989HA43, 1989HA08, 1989PA06, 1989PO06, 1989SA10, 1989SE03, 1989SU05, 1989TU1A, 1989YO02). Muon and neutrino capture and reactions: (1983GM1A, 1984KU20, 1984KU11, 1984MI11, 1984RU12, 1985AG1C, 1985AR1B, 1985BO1U, 1985GR1A, 1985KI01, 1985MAZZ, 1985PA05, 1985PA12, 1986DA1J, 1986DO06, 1986DU06, 1986FI1G, 1986KE1Q, 1986KU05, 1986LI13, 1986MA16, 1986PA06, 1987BR1L, 1987FU13, 1987HA1Q, 1987KO1P, 1987KR1L, 1987MI17, 1987SU06, 1987VA1P, 1988AL1O, 1988BO1X, 1988BR24, 1988DO05, 1988FU08, 1988MI11, 1988MI20, 1989AR1I, 1989DR1A, 1989GM1A, 1989KR1C, 1989MI1I, 1989NA01). Pion capture and reactions (See also reactions 28 and 34): (1981HO14, 1983AB1B, 1983AB1C, 1983AG1B, 1983AK1A, 1983BU1D, 1983GM1A, 1983KO1M, 1983MA16, 1984AL1K, 1984AL1L, 1984AS05, 1984BA1L, 1984BA2L, 1984BA1M, 1984BE28, 1984BE1Q, 1984BE1R, 1984BO1L, 1984BO1H, 1984BU11, 1984CE1D, 1984CH26, 1984CO16, 1984CO1D, 1984ER06, 1984GE1A, 1984GI1D, 1984GM01, 1984GR27, 1984JI03, 1984KA31, 1984KO1P, 1984LE11, 1984LI03, 1984MA1T, 1984MA1G, 1984MA1U, 1984MI11, 1984OH04, 1984RI12, 1984RO1D, 1984SA1H, 1984SC1B, 1984TO1A, 1984ZI1B, 1985AB1E, 1985ALZX, 1985AM1B, 1985AR15, 1985AS02, 1985AZ1A, 1985AZ1B, 1985BA2F, 1985BA1V, 1985BE1C, 1985BI01, 1985BI04, 1985BU1G, 1985CO11, 1985CO16, 1985DI02, 1985FU06, 1985FU14, 1985GI05, 1985GR1E, 1985GU13, 1985KA22, 1985KO06, 1985KO2C, 1985LA20, 1985LE1E, 1985LI1E, 1985MA1G, 1985MA1K, 1985ME1M, 1985MI04, 1985MI1L, 1985MO1H, 1985MO1M, 1985OH09, 1985RI04, 1985RO17, 1985RO1M, 1985SA06, 1985SE21, 1985SM06, 1985TA17, 1985TA24, 1985TO15, 1985TO14, 1985VA17, 1986AB1J, 1986AG1C, 1986ALZL, 1986AN40, 1986AR1F, 1986AS1A, 1986BA3E, 1986BA81, 1986BA3H, 1986BE22, 1986BE2L, 1986BL05, 1986BO03, 1986BO1N, 1986CH39, 1986CH1Z, 1986CH1J, 1986CO1V, 1986CZ01, 1986DI07, 1986DU1M, 1986ER1A, 1986FA03, 1986FO03, 1986GA33, 1986GA14, 1986GH1A, 1986GI13, 1986GR1K, 1986HA34, 1986HA26, 1986IV1A, 1986KA1J, 1986KH03, 1986KI1D, 1986LAZL, 1986MC04, 1986MI25, 1986MO1M, 1986MO1J, 1986MO26, 1986NA03, 1986OS01, 1986OS1H, 1986OS03, 1986PE1L, 1986PE05, 1986PR1C, 1986PR01, 1986RA1J, 1986RO03, 1986SU18, 1986TA1T, 1986VO17, 1986VO1H, 1986WA26, 1986WH02, 1986YO05, 1986ZO1A, 1987AB12, 1987AB1E, 1987AG1C, 1987AL1I, 1987AL26, 1987AN14, 1987AP1A, 1987AR1P, 1987AS1E, 1987BA2Q, 1987BE2A, 1987BE2B, 1987BL07, 1987BO1D, 1987BO1E, 1987BO1X, 1987BU20, 1987CH21, 1987CH1N, 1987CH24, 1987CH29, 1987CL02, 1987CO20, 1987EJ02, 1987FA05, 1987GA08, 1987GA11, 1987GI01, 1987GI1B, 1987GI1C, 1987GM02, 1987GM04, 1987GU07, 1987GU1I, 1987HA40, 1987HE04, 1987HO08, 1987HU13, 1987JO1B, 1987KA39, 1987KH1B, 1987KO30, 1987LE1B, 1987LO1F, 1987MA1I, 1987MA1Z, 1987MO1M, 1987NA04, 1987PI1B, 1987RA1H, 1987ST1E, 1987WE1A, 1987WU1B, 1988AB05, 1988AB1G, 1988AM04, 1988BA2G, 1988BE1V, 1988BE2D, 1988BE2F, 1988BU16, 1988CH49, 1988CH24, 1988CH31, 1988CU1C, 1988DH1A, 1988ER04, 1988ER1B, 1988FR02, 1988FR1D, 1988FR10, 1988FR1J, 1988GIZU, 1988GO13, 1988GO08, 1988GO14, 1988GR1E, 1988HA07, 1988HA12, 1988EL06, 1988IT02, 1988JO1E, 1988KH01, 1988KIZW, 1988KY1A, 1988LE1G, 1988MA27, 1988MA37, 1988MO23, 1988OH04, 1988OS1A, 1988PE1F, 1988PO1H, 1988RA1H, 1988RO1M, 1988SA24, 1988SA31, 1988WI1B, 1988WI1I, 1988YOZZ, 1989AR1K, 1989BA06, 1989BA1R, 1989BRZX, 1989EJ1A, 1989EN1B, 1989GH1B, 1989GO09, 1989GR06, 1989HA07, 1989KH01, 1989MO1D, 1989NA01). Kaons and other mesonscapture and reactions (see also 19reaction 35): (1983AK1A, 1983AR1F, 1983GE1C, 1983TO21, 1984AB04, 1984AL1H, 1984BA2L, 1984BA1M, 1984BO1H, 1984CO21, 1984GI1E, 1984IW1B, 1984MA1G, 1984SI13, 1984TO1B, 1984YA04, 1984ZO02, 1985AB1E, 1985BE31, 1985BE62, 1985CO1H, 1985CO14, 1985CO05, 1985DA1D, 1985DI06, 1985DO1G, 1985GA1E, 1985GA1C, 1985GR10, 1985IA01, 1985MI04, 1985SH1H, 1985SI09, 1985WA1N, 1985YA01, 1985YA07, 1985ZH13, 1985ZH11, 1986AB07, 1986AG1B, 1986BA3L, 1986BA81, 1986BE1P, 1986BE2J, 1986BE42, 1986BI1G, 1986CH1P, 1986CH1I, 1986CO1U, 1986DA1G, 1986DA1B, 1986DO1B, 1986FI1A, 1986GA33, 1986GA14, 1986GA1H, 1986HA1Y, 1986HA34, 1986HA26, 1986HA39, 1986HU1B, 1986KA1J, 1986KI1K, 1986KI1D, 1986KO2D, 1986MA1J, 1986MI1N, 1986MO1J, 1986PE1L, 1986TA11, 1986YA1T, 1986ZH1E, 1986ZO1A, 1987AP1A, 1987BEYQ, 1987BE14, 1987BE1S, 1987BL1L, 1987CH10, 1987EJ02, 1987FA1A, 1987HA40, 1987KO30, 1987LE1B, 1987PI1B, 1987PO1H, 1987SM1A, 1987WU1B, 1987WU05, 1988BA1F, 1988BR16, 1988CH49, 1988FA1B, 1988GA1A, 1988HA07, 1988HA41, 1988HA44, 1988KO36, 1988MA09, 1988MO1B, 1988MO14, 1988MO23, 1988PA1B, 1988PE1F, 1988PO1H, 1988RO11, 1988TA29, 1988TA14, 1988WA1B, 1988YA05, 1989BA06, 1989EJ1A, 1989HA07). Hypernuclei: (1983SH1E, 1984AL1H, 1984AS1D, 1984BA1M, 1984BA1N, 1984BO1H, 1984MA1G, 1984MA1U, 1984MI1E, 1984SA1J, 1984ZO02, 1985AH1A, 1985GA1E, 1985GR10, 1985MI04, 1985OS1C, 1985WA1N, 1986BA3L, 1986BA1H, 1986AB81, 1986BI1G, 1986CO1U, 1986DA1G, 1986DA1B, 1986DO1B, 1986DU1M, 1986DU1P, 1986ER1A, 1986FE1A, 1986FR1J, 1986GA33, 1986GA14, 1986GA1H, 1986HA1Y, 1986HA34, 1986HA39, 1986HE01, 1986HU1B, 1986KO1A, 1986MI1N, 1986OS1G, 1986PE1L, 1986PO1H, 1986SZ1A, 1986YA1T, 1986ZO1A, 1987BA2K, 1987DA1F, 1987DA30, 1987DO1B, 1987EJ02, 1987MA08, 1987MA2A, 1987MI38, 1987PI1C, 1987PO1H, 1987RU1A, 1988BA1F, 1988BA1G, 1988BA82, 1988BO1P, 1988CH48, 1988DL1A, 1988GA1A, 1988GA1I, 1988GR1B, 1988HA07, 1988HA44, 1988MA09, 1988MA1G, 1988MO1B, 1988MO14, 1988MO23, 1988MO1L, 1988PE1F, 1988PO1H, 1988TA29, 1988WA1B, 1989BA06, 1989EJ1A, 1989KI25, 1989MR01). Antinucleon interactions (see also reaction 38): (1984BA39, 1984CL1C, 1984DA1J, 1984DA23, 1984DO1E, 1984GA26, 1984KR22, 1984RI1D, 1984SA1M, 1984SU07, 1984VO1D, 1985AB1E, 1985BA09, 1985BA51, 1985CA16, 1985DA1D, 1985DA06, 1985DA24, 1985DA1G, 1985DO1E, 1985DU05, 1985HE24, 1985KU04, 1985KU08, 1985LI1J, 1985NA14, 1985PI14, 1985SU11, 1985VO06, 1986AU1D, 1986BA22, 1986BO26, 1986BU1J, 1986DI04, 1986DO20, 1986DU10, 1986FR10, 1986HE05, 1986IN01, 1986JA04, 1986MA46, 1986MC04, 1986MO1J, 1986SP01, 1986ZA06, 1987BA21, 1987BE26, 1987DA12, 1987DA1D, 1987GR1I, 1987HE04, 1987IS03, 1987MA04, 1987MA46, 1987SM1A, 1987VO1B, 1987YA1E, 1987ZA08, 1988DA07, 1988DE40, 1988GO13, 1988LI1O, 1988OK03, 1989AR1K, 1989CH13, 1989MA24, 1989MU1D). Other topics: (1984CH1L, 1984CL11, 1984CO16, 1984GR18, 1984JE02, 1984LO05, 1984SH1X, 1985AN28, 1985AR07, 1985AR1B, 1985BU1F, 1985CI04, 1985KE1G, 1985KU22, 1985PA1M, 1985SHZL, 1985TH1D, 1986AL1T, 1986BE23, 1986BE39, 1986BI01, 1986DU06, 1986FO03, 1986KU11, 1986KE1P, 1986KU1B, 1986KU1P, 1986SA02, 1986SH2E, 1986WE1G, 1986YA1F, 1987AB21, 1987FUZZ, 1987HO07, 1987KU1I, 1987MO14, 1987PR01, 1987ZE05, 1988BO04, 1988FL1A, 1988HA38, 1988JA13, 1988KW02, 1988MO1H, 1988OH01, 1988OR1C, 1988OS1E, 1988RO18, 1988RU1B, 1989BA60, 1989CE01, 1989FI04, 1989JI04, 1989OR02, 1989RE1C, 1989RO01). Groundstate properties of ^{12}C: (1984AN1B, 1984BA2F, 1984BR25, 1984LO05, 1984RU12, 1985AN16, 1985AN28, 1985BE59, 1985CL1A, 1985GO1A, 1985KO02, 1985MI23, 1985OR01, 1985SA32, 1985SA30, 1985SH1A, 1985TA18, 1986AL1T, 1986AN35, 1986EL1A, 1986HE26, 1986KA2C, 1986KU1B, 1986LE16, 1986NI01, 1986RO03, 1986SA32, 1986SY1A, 1986WI04, 1987AB03, 1987AL05, 1987BL18, 1987BO42, 1987ER1F, 1987FU1D, 1987GI1C, 1987GU1C, 1987HA30, 1987JI01, 1987KI1C, 1987PR03, 1987RA01, 1987SA15, 1987ZE05, 1988BI1A, 1988CU1C, 1988DA1J, 1988DZ1A, 1988GU03, 1988HA38, 1988JO1C, 1988ME09, 1988OH01, 1988RA1G, 1988SP1A, 1988TA10, 1988VA03, 1988WO04, 1989BE03, 1989OR05, 1989RO01). Isotopic abundance: (98.90 ± 0.03)% (1984DE53).
The interaction nuclear radius of ^{12}C is 2.61 ± 0.02 fm (1985TA18). [See also for derived nuclear matter, charge and neutron matter r.m.s. radii.] See also (1989SA10). ^{12}C*(4.44): Q = 6 ± 3 e · fm^{2}, indicating a substantial oblate deformation (1983VE01).
The excitation functions for some final states in ^{11}B and ^{11}C (reactions (a) and (b)) are structureless while others (to states with J^{π} = 3/2^{}, 5/2^{}, 5/2^{+}) exhibit pronounced structures. The most prominent of these is observed at E(^{6}Li) = 8.4 MeV [^{12}C*(32.4)] in the p_{2} and n_{2} yields with a width Γ_{c.m.} ≈ 1 MeV (1987DO05). Reaction (d) has been studied for E(^{6}Li) = 2.4 to 6.7 MeV in a kinematically complete experiment (1988LA11). See also (1984LA19, 1987LA25). For reactions (e) and (f) see (1983WA09). Broad structures have been observed in the elastic scattering at E(^{6}Li) ≈ 13 and 26 MeV: see (19880AJ01). See also (1985AJ01), ^{6}Li and ^{8}Be in (1988AJ01), ^{11}B and ^{11}C here, (1985NO1A), (1988WE20) and (1988MC1E; applied).
This reaction, of great importance to nucleosynthesis, has been studied by (1985CA41, 1986LA16, 1987DE13). See also the "General" section here.
Observed resonances are displayed in 12.8 (in PDF or PS). ^{12}C*(28.2) appears to be formed by s and dwave capture. The γ_{0} and γ_{2} transitions to the 0^{+} states ^{12}C*(0, 7.7) are strong and show a similar energy dependence. A strong nonresonant contribution is necessary to account for the γ_{1} yield. The resonance structure appears to confirm the role of 3p3h configurations for ^{12}C excitations somewhat above the giant resonance region. The γ_{3} yield is relatively unstructured: see (1980AJ01). See also (1984MAZP, 1985BL1B).
Excitation functions for neutrons, production cross sections for ^{11}C and polarizations have been measured for E(^{3}He) = 1.2 to 10 MeV for several neutron groups. No sharp structure is observed but there is some suggestions from angular distribution data and excitation functions at forward angles for a structure (Γ ≈ 350 keV) at E(^{3}He) ≈ 2 MeV: E_{x} = 27.8 MeV. The total cross section for ^{11}C production shows a broad maximum, σ = 113 mb at E(^{3}He) = 4.3 MeV. In the range E(^{3}He) = 5.7 to 40.7 MeV it decreases monotonically. Excitation functions and angular distributions for protons (reaction (b)) have been measured for E(^{3}He) = 1.0 to 10.2 MeV for a number of proton groups. No pronounced structures are reported. See also (1986SL1B; theor.). Analyzing powers have been measured at E(pol. ^{3}He) = 33.3 MeV for nine deuteron groups (reaction (c)). The cross section for groundstate tritons (reaction (d)) increases monotonically for E(^{3}He) = 2.5 to 4.2 MeV and then shows a broad maximum at E(^{3}He) ≈ 4.5 MeV. The elastic scattering excitation function (reaction (e)) decreases monotonically for E(^{3}He) = 4.0 to 9.0 MeV and 15.0 to 21.0 MeV. At θ_{c.m.} = 111° a slight rise is observed for E(^{3}He) = 19 to 21 MeV. Polarization measurements have been reported at E(^{3}He) = 18, 31.4 and 32.8 MeV. Excitation functions for the α_{0} group (reaction (f)) have been reported for E(^{3}He) = 2 to 10 MeV. Analyzing powers have been measured at E(pol. ^{3}He) = 33.3 MeV. For reaction (g) see (1986LA26, 1987WA25). See also (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01) for references and for additional work, ^{11}B and ^{11}C here, and ^{8}Be, ^{9}Be, ^{9}B and ^{10}B in (1988AJ01).
Neutron groups have been observed to ^{12}C*(0, 4.4, 7.7, 9.6, (10.1), (10.8)). Angular distributions have been measured at many energies in the range E_{α} = 1.75 to 23 MeV [see (1968AJ02, 1975AJ02)] and at 28 and 32 MeV (1985GUZQ; prelim.; n_{0→3}). [The work at E_{α} = 35 MeV reported in (1985AJ01) has not been published: see, however, Fig. 1 in (1986AS02).] See also (1985CA41, 1988CA26; astrophysics) and (1986PH1C, 1987TC1A; applications).
At E(^{6}Li) = 32 MeV angular distributions have been studied to ^{12}C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 14.1). There is no indication of the T = 1 states. ^{12}C*(9.64) is relatively strongly populated (1986AS02; FRDWBA). See also (1980AJ01).
See (1985AJ01).
At E(^{3}He) = 13 MeV neutron groups are observed to ^{12}C*(0, 4.4, 7.7, 16.1, 17.8) and to excited states at E_{x} = 23.53 ± 0.04 [Γ < 0.4 MeV] and 27.611 ± 0.020 MeV. The latter is formed with a 0° cross section of ≈ 200 μb/sr and is taken to be the first 0^{+}, T = 2 state of ^{12}C (1974GO23).
The (d, γγ) excitation functions [via the J^{π} = 1^{+}, T = 1 state at E_{x} = 15.1 MeV] has been measured for E_{d} = 2.655 to 2.91 MeV. The nonresonant yield of 15 MeV γrays is due to a direct capture process or to a very broad resonance: see (1975AJ02).
The thintarget excitation function in the forward direction (reaction (a)) in the range E_{d} = 0.3 to 4.6 MeV shows some indication of a broad resonance near E_{d} = 0.9 MeV. Above E_{d} = 2.4 MeV, the cross section increases rapidly to 210 mb/sr at 3.8 MeV, and then remains constant to 4.6 MeV. Excitation functions have also been measured for E_{d} = 3.2 to 16.0 MeV. Thick target yields for 4.3 MeV γrays for E_{d} = 111 to 170 keV have also been studied and astrophysical Sfactors have been calculated. In reaction (b) yields of protons have been measured for E_{d} = 91 keV to 12 MeV: no clear resonance structure is observed. See also ^{11}B, ^{11}C here and (1968AJ02, 1975AJ02, 1985AJ01).
The yield of elastically scattered deuterons has been measured for E_{d} = 1.0 to 2.0 MeV (there is some suggestion of resonances) and for E_{d} = 14.0 to 15.5 MeV. Excitation functions for the deuterons to ^{10}B*(1.74, 2.15) [J^{π}; T = 0^{+}; 1 and 1^{+}; 0, respectively] have been measured at several angles for E_{d} = 4.2 to 16 MeV: they are characterized by rather broad, slowly varying structure: see (1980AJ01) [see also for polarization measurements]. See also ^{10}B in (1988AJ01).
Excitation functions have been measured for the α_{0} and α_{1} groups for E_{d} = 0.4 to 12 MeV. Broad maxima in the α_{0} yield are reported at E_{d} ≈ 1 (Γ ≈ 0.5), 2 and 4.5 MeV (Γ ≳ 1 MeV) as well as, possibly, at 6 MeV. Involvement of the isoscalar giant quadrupole resonance [E_{x} ≈ 28 MeV, Γ ≈ 4 MeV] is suggested: see (1980AJ01). See also ^{8}Be in (1988AJ01) and (1988KA1M; theor.).
12.9 (in PDF or PS) displays the proton groups observed in this reaction , and the work on their αdecay. For a study of the chargedependent matrix element between ^{12}C*(12.7, 15.1) see 12.10 (in PDF or PS).
Angular distributions have been measured at E_{α} = 15.1 to 25.2 MeV [see (1980AJ01)], 29.5 MeV (1983VA28; d_{0}, d_{1}) and 31.2 MeV (1984KO1Q; d_{0}, d_{1}). For dγ_{4.4} angular correlation studies see (1987VA04, 1988IG04, 1988VA1D). See also (1984BE23; theor.).
At E(^{6}Li) = 4.9 MeV angular distributions have been obtained for the αparticles to ^{12}C*(0, 4.4, 7.7, 9.6). The population of ^{12}C*(11.8, 12.7) is also reported, as is that of ^{12}C*(15.11) [T = 1]: see (1975AJ02).
Angular distributions involving ^{12}C*(0, 4.4) have been measured at several energies, to E(^{14}N) = 93.6 MeV: see (1980AJ01). See also (1984MA1R).
In view of the complexity of the availiable information on these three reactions, we will first summarize the experimental results and then review the evidence for the parameters of ^{12}C states observed as resonances: see 12.11 (in PDF or PS). See (1975AJ02, 1980AJ01) for references. (a) In the range 4 < E_{p} < 14.5 MeV σ(γ_{0}) is dominated by the great dipole resonance at E_{p} = 7.2 MeV (E_{x} = 22.6 MeV, Γ_{c.m.} = 3.2 MeV), while the giant resonance in γ_{1} occurs at E_{p} ≈ 10.3 MeV (E_{x} = 25.4 MeV, Γ_{c.m.} ≈ 6.5 MeV). Absolute cross section measurements from E_{p} = 5 to 14 MeV suggest that dσ/dΩ (90°)_{L} = 13.1 ± 1.3 μb/sr be used as a standard at the E_{p} = 7.25 MeV peak of the GDR. A study of the giant dipole resonance region with polarized protons (E_{p} = 6 to 14 MeV) sets new limits on the configuration mixing in the γ_{0} giant resonance. The analysis of γ_{1} is more complicated: the asymmetry results are consistent either with a single J^{π} = 2^{} state or with interference of pairs of states such as (1^{}, 3^{}), (2^{}, 3^{}) and (1^{}, 2^{}). The 90° yield of γ_{0}, γ_{1}, γ_{2} and γ_{3} [to ^{12}C*(0, 4.4, 7.7, 9.6)] has been studied by (1977SN01): the γ_{2} yield shows a peak at E_{p} ≈ 14.3 MeV with a cross section ≈ 2.3% that of γ_{0} [in γ_{0} yield, E_{res} = 15.0 MeV (1977SN01)] and perhaps as well a low intensity structure at E_{p} = 11.8 MeV. The γ_{3} yield exhibits two asymmetric peaks at E_{p} = 12.5 and 13.8 MeV (Γ ≈ 0.7 and 2.5 MeV) and a weaker structure at ≈ 9.8 MeV (1977SN01). At E_{pol. p} = 50 MeV, angular distributions and analyzing power measurements are reported to ^{12}C*(0, 4.4, 9.6, 18.8 ± 0.5 [u], 22.3 ± 1.0 [u]) by (1985NO01) [u = unresolved]. Measurements are also reported at E_{pol. p} = 28.5 MeV (1984BL10) and 40 to 80 MeV (1986EJ1A, 1986SH1Y; prelim., γ_{0}, γ_{1}). (1988HA04) have studied the γ_{0} group for E_{pol. p} = 20 to 100 MeV. See also (1985HA05). In earlier work (1982WE08) studied the γ_{0} and γ_{1} yields for E_{p} = 8 to 60 MeV and the γ_{19} yield for E_{p} = 23 to 60 MeV. Giant resonances based on various states of ^{12}C have been reported at E_{x} = 22.5 and 25.5 MeV [γ_{0}], 25.5, 27.4 and (31) MeV [γ_{1}], 27.4, 31 and (37) MeV [γ_{3}], as well as in the γyield to higher states: see (1985AJ01). The γ_{19} yield shows a structure at E_{p} ≈ 43 MeV (1983AN16; E_{p} = 18 to 45 MeV; also γ to ^{12}C*(0, 4.4, 9.6, 12.7 [u], 15.5 [u]). (b) Excitation functions have been measured for E_{p} = 3.0 to 24 MeV: see (1980AJ01, 1985AJ01) and 12.11 (in PDF or PS) and 12.12 (in PDF or PS) here. (c) This reaction has been studied at energies to 20 MeV. The cross sections for the reactions vie ^{8}Be_{g.s.} and ^{8}Be*(2.9) [α_{0}, α_{1}] have been determined for E_{c.m.} = 22 to 1100 keV. The total cross section shows the 162 keV resonance and a broad peak centered at 600 keV. At E_{c.m.} = 300 keV σ(α_{0}) = 1.03 ± 0.06 mb and σ(α_{1}) = 165 ± 10 mb (1987BE17). The parameters of the 162 keV resonance are E_{res}(c.m.) = 148.3 ± 0.1 keV, Γ_{c.m.} = 5.3 ± 0.2 keV (1987BE17), 149.8 ± 0.2 keV, 5.2^{+0.5}_{0.3} keV (1979DA03). Derived Svalues lead to S(0) = 197 ± 12 MeV · b (1987BE17). This reaction is of possible interest for fusion reactors. See also ^{8}Be in (1988AJ01), (1985NO1G, 1986KU18), (1984BR1L, 1984SN01, 1985DO1F, 1986SN1B, 1986WE1D, 1988HA1W), (1983SG1B, 1984HA1J, 1986KA1U, 1986PR1D, 1986ZI01, 1988KI1C; applications), (1983HA1B, 1984YA1A, 1985CA41, 1987AS05, 1988CA26; astrophysics) and (1984CA18, 1984SE16, 1985GO1B, 1985KI16, 1985RA10, 1987AS05, 1987KI1C, 1987KO1X; theor.). The parameters of the observed resonances are displayed in 12.11 (in PDF or PS). The following summarizes the information on the lowlying resonances: for a full list of references see (1968AJ02, 1980AJ01, 1985AJ01). E_{p}= 0.16 MeV [^{12}C*(16.11)]. This is the J^{π} = 2^{+}; T = 1 analog of the first excited states of ^{12}B and ^{12}N. The γdecay is to ^{12}C*(0, 4.4, 9.6), and also ^{12}C*(12.71) [see 12.7 (in PDF or PS)]: the angular distribution of γ_{3}, together with the known αdecay of ^{12}C*(9.6), fix J^{π} = 3^{} for the latter. E_{p}= 0.67 MeV [^{12}C*(16.57)]. The proton width [Γ_{p} ≈ 150 keV] indicates swave protons and therefore J^{π} = 1^{} or 2^{}. This is supported by the near isotropy of the two resonant exit channels, α_{1} and γ_{1}. The α_{1} cross section indicates 2J + 1 ≥ 5: therefore J^{π} = 2^{}. [This is consistent with the results of an ααcorrelation study via ^{8}Be*(2.9)]. The γ_{1} E1 transition has M^{2} ≈ 0.1 W.u., suggesting T = 1. E_{p}= 1.4 MeV [^{12}C*(17.23)]. (2J + 1)Γ_{γ0} ≥ 115 eV. This indicates J^{π} = 1^{}, with T = 1 most probable. J^{π} = 1^{} is also required to account for the interference at lower energies in α_{0} and γ_{0} and is consistent with the ααcorrelation results. Two solutions for Γ_{p} are possible; the larger (chosen for 12.11 (in PDF or PS)) is favored by elastic scattering data. E_{p}= 2.0 MeV [^{12}C*(17.8)]. The resonance in the yield of α_{0 } requires natural parity, the small αwidths suggest T = 1. For J^{π} = 1^{} or 3^{} the small γwidths would be surprising; J^{π} = 2^{+} would lead to a larger anomaly than is observed. J^{π} is then 0^{+}, T = 1. (1982HA12) [E_{p} = 0.82 to 2.83 MeV] report E_{x} = 17.80 MeV [Γ_{c.m.} = 96 ± 5 keV] decays via a 5.10 ± 0.03 MeV γray to ^{12}C*(12.71): Γ_{γ} = 3.7 ± 1.5 eV. The angular distribution is isotropic, as expected. E_{p}= 2.37 MeV [^{12}C*(18.13)]. Seen as a resonance in the yield of 15.1 MeV γrays: σ_{R} = 0.77 ± 0.15 μb, Γ_{c.m.} = 600 ± 100 keV, (2J + 1) Γ_{γ} ≥ 2.8 ± 0.6 eV. The results are consistent with J^{π} = 1^{+}, T = 0, but interference with a nonresonant background excludes a definite assignment. E_{p}= 2.62 MeV [^{12}C*(18.38)]. The resonance for α_{0} requires natural parity; the presence of a large P_{4} term in the angular distribution requires J ≥ 2 and l_{p} ≥ 2. (1982HA12) report E_{x} = 18.38 MeV, Γ_{c.m.} ≈ 400 keV, Γ_{γ} (to ^{12}C*(9.6)) = 5.7 ± 2.3 eV, consistent with J^{π} = 3^{}; T = 1. The total peak cross section is 4.2 ± 1.7 μb. Transitions to ^{12}C*(0, 4.4) are also observed: Γ_{γ} ≈ 2 × 10^{3} eV and 3.2 ± 1.0 eV, respectively. E_{p}= 2.66 MeV [^{12}C*(18.39)] is not seen here: see ^{11}B(p, p). E_{p}= 3.12 MeV [^{12}C*(18.81)]. The angular distribution of γ_{0} indicates E2 radiation, J^{π} = 2^{+}. This assignment is supported by the angular correlation in the cascade γ_{1} and by the behavior of σ(α_{0}); T = 1 is suggested by the small Γ_{α}. The yield of γ_{3} (to ^{12}C*(9.6)) shows a peak corresponding to E_{x} ≈ 18.9  19.0 MeV. It may be due to ^{12}C*(18.8) with an energy shift due to interference. The structure near E_{p} = 3.5  3.7 MeV [^{12}C*(19.2, 19.4)] seems to require at least two levels. The large Γ_{γ0} requires that one be J^{π} = 1^{}, T = 1 and interference terms in σ(α_{0}) require another to have even spin and even parity: J^{π} = 2^{+}, T = 0 is favored. (1982WR01) report that they do not observe any evidence for an isospin mixed doublet near E_{x} = 19.5 MeV [E_{p} = 2.9 to 4.6 MeV (60° and 90°)]. Resonances at E_{p} = 4.93 and 5.11 MeV, seen in σ(γ_{1}) also appear in σ(α_{1}), but not in σ(α_{0}). Angular distributions suggest J^{π} = 2^{+} or 3^{} for the latter [^{12}C*(20.64)]; the strength of γ_{1} and absence of γ_{0} favors J^{π} = 3^{}, T = 1. The first seven T = 1 states in ^{12}B and ^{12}C have been identified by comparing reduced proton widths obtained for this reaction and reduced widths obtained from the (d, p) and (d, n) reactions: see 12.12 (in PDF or PS) in (1980AJ01).
Excitation functions have been studied from threshold to 27.5 MeV [see (1980AJ01, 1985AJ01)] and at E_{p} = 13.7 to 14.7 MeV (1985SC08; n_{0} → n_{3}, n_{4+5}, n_{6}, n_{7}) and 16 to 26 MeV (1985GR09; n_{0} → n_{3}). See also (1986AI04). At the lower energies many resonances are observed: see 12.12 (in PDF or PS). Polarization measurements have been carried out for E_{pol. p} = 7.0 to 26.5 MeV [see (1980AJ01, 1985AJ01)]. For highenergy interactions see (1984BA1R, 1984BA1U). See also ^{11}C, (1989RA09), (1985CA41; astrophysics) and (1985RA10; theor.).
Anomalies and maxima observed in the excitation functions of p_{0} → p_{3} are displayed in 12.12 (in PDF or PS). Studies of the scattering have been reported at E_{p} = 1.8 to 47.4 MeV [see (1980AJ01, 1985AJ01)] and at E_{c.m.} ≈ 0.15 to 1.1 MeV (1987BE17; p_{0}). A study of the yield of γrays is reported to lead to ^{12}C*(18.98, 19.93, 20.63) (1988ABZW; prelim.). A review of the evidence on the states with 20.2 < E_{x} < 22.5 MeV suggests that in all the channels and throughout this energy range a strong 2^{+} background is observed, which may be the lowenergy tail of the isoscalar giant quadrupole resonance (1983BO19). For polarization measurements [E_{p} = 1.9 to 155 MeV] see (1975AJ02, 1980AJ01, 1985AJ01). For reaction (b) see (1985AJ01) and ^{10}B in (1988AJ01). For studies of highenergy interactions see (1984BA1U, 1984BA1T). See also (1985MUZZ), (1986BA88) and (1985RA10, 1987RA14; theor.).
Reported neutron groups are displayed in 12.13 (in PDF or PS). Angular distributions have been studied for E_{d} = 0.5 to 12 MeV [see (1968AJ02, 1975AJ02, 1985AJ01)] and at E_{pol. d} = 79 MeV (1985FO05, 1987FO22); to ^{12}C*(0, 4.4, 9.6, 12.7, 15.1; DWBAEFR). For polarization measurements see (1987FO22, 1986FO08) and ^{13}C in (1991AJ01). For angular correlation studies see (1980AJ01) and (1985NE01) [ 12.13 (in PDF or PS)].
Observed deuteron groups are displayed in 12.13 (in PDF or PS). Angular distributions have been studied at E(^{3}He) = 5.1 to 44 MeV [see (1975AJ02, 1980AJ01)] and at 18.3 and 22.3 MeV (1988IG03; d_{0}, d_{1}; also d_{1}γ angular correlations). See also (1987BA2B, 1987ZE02; theor.).
Angular distributions have been studied in the range E_{α} = 15.1 to 120 MeV [see (1980AJ01, 1985AJ01)] and at E_{α} = 30.1 (1983VA28; t_{0}, t_{1}, t_{2}) and 31.2 MeV (1984KO1Q; t_{0}, t_{1}). Angular correlation measurements (t_{1}, γ) are reported at E_{α} = 21 to 30 MeV: see (1987VA04, 1988IG04, 1988VA1D). See also (1987LE33) and (1984BE23, 1985ZE04, 1987BA2B, 1987ZE02, 1989BA90; theor.).
At E(^{7}Li) = 34 MeV, angular distributions have been measured for the groups to ^{12}C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 15.1, 16.1, 18.35) (1983NE11). It is concluded on the basis of this and other work, that the group corresponding to E_{x} = 18.35 ± 0.05 MeV (Γ = 350 ± 50 keV) consists of unresolved states with J^{π} = 3^{} (T = 1) and 2^{} (T = 0 plus some mixing of T = 1) (1983NE11; see for spectroscopic factors): no states were observed with E_{x} > 18.35 MeV. See also (1987CO16, 1988BEYJ).
Angular distributions involving ^{12}C*(0, 4.4) and ^{10}Be*(0, 3.4) have been measured at E(^{11}B) = 11 MeV (1985PO02).
See (1980AJ01). See also (1984CL09; theor.).
The decay is mainly to ^{12}C_{g.s.}; branching ratios to ^{12}C*(0, 4.4, 7.7, 10.3) are displayed in 12.14 (in PDF or PS). All the observed transitions are allowed. The halflife is 20.20 ± 0.02 ms (1978AL01). ^{12}C*(7.7) [J^{π} = 0^{+}] is of particular interest for helium burning processes in stars: Γ_{rad} = 3.41 ± 1.12 meV. A search for transitions to ^{12}C*(12.7) has been unsuccessful: see (1968AJ02, 1975AJ02). The shapes of the βspectra of ^{12}B and ^{12}N have been analyzed. The results are in agreement with CVC and with the absence of secondclass induced tensor currents: see (1980AJ01). See also reaction 60 here.
The total absorption, mainly (γ, n) + (γ, p), is dominated by the giant resonance peak at 23.2 MeV, Γ = 3.2 MeV [σ_{max} = 21 mb] and by a smaller structure at 25.6 MeV, Γ ≈ 2 MeV [σ_{max} ≈ 13 mb]: see (1968AJ02, 1975AJ02, 1980AJ01) for a detailed listing of the earlier references and results. See also (1984GH1A, 1985GH1B). The (γ, n) cross section shows a giant resonance, σ_{max} ≈ 7  8 mb, centered at about 23 MeV and consisting of an ≈ 1 MeVwide group at 22.3 MeV and an ≈ 2 MeVwide group at ≈ 23.3 MeV. A secondary maximum occurs at 25.5 MeV, Γ ≈ 2 MeV. There is also evidence of other structure at ≈ 30  31 and possibly at ≈ 35 MeV: see (1988DI02) and B.L. Berman, private communication. The (γ, n_{0}) cross section has been measured at 90° for 21 < E_{x} < 40 MeV and compared with the (γ, p_{0}) cross section: the isospin mixing averages about 2% in intensity and shows structure at the giant resonance. Angular distributions of n_{0} measured over the giant resonance region indicate that the main excitation mechanism is of a 1p_{3/2} → d_{5/2} E1 singleparticle character. No significant E2 strength is observed: see (1980AJ01). Differential cross sections at θ_{lab} = 65° have been measured for the n_{0+1} and n_{2→9} groups for E_{γ} = 33.7 to 99.4 MeV (1988HA01). See also the discussion in (1985FU1C). The (γ, 2n) cross section (reaction (b)) is very much smaller than that for (γ, n): the highest value is 0.15% of the maximum value for reaction (a) in the energy range E_{γ} = 20 to 140 MeV: see (1980AJ01, 1985AJ01). See also (1985AH06, 1985GI1G, 1985HO27, 1985PY01), (1989BO1F; astrophysics) and (1984CA18, 1984MO13, 1984VA1G, 1985BO12, 1985GO1A, 1985KO2K, 1985VA1C, 1986VA14, 1987BR21, 1987FE05, 1987GO37, 1987KI1C, 1987VA35, 1988CO1G; theor.).
The photoproton cross section exhibits two broad peaks, the giant resonance peak at 22.5 MeV, Γ = 3.2 MeV, σ_{max} = 13.1 ± 0.8 mb and a 2 MeV broad peak at 25.2 MeV, σ_{max} = 5.6 ± 0.3 mb: see (1976CA21) and 12.19 (in PDF or PS) in (1968AJ02). The (γ, p_{0}) cross section at the giant resonance is 11.0 ± 1.1 mb (1986KE06). While the E1 component dominates in the GDR, a 2% E2 contribution may possibly be present (1976CA21). In contrast with the giant resonance peak in the (γ, n) cross section, the (γ, p) cross section shows a strong peak in the center of the broad giant resonance peak. Above 24.5 MeV the ground state (γ, p) and (γ, n) excitation functions have the same shape up to at least 36 MeV: see (1985FU1C). There is agreement between the (γ, p) results and those from the inverse reaction ^{11}B(p, γ_{0}) [see reaction 17] when the population of ^{11}B*(4.4, 5.0) is taken into account. See also ^{11}B and (1986AN25, 1986MC15, 1988SH08). At E_{γ} = 28 MeV the branching ratios to ^{11}B*(0, 2.12, 4.4 + 5.0) are, respectively, (76 ± 4)%, (13 ± 1.3)% and (11 ± 1.2)% (1989FE01). See also reaction 30. For the proton momentum spectrum at E_{γ} = 357 ± 10 MeV see (1984HO24). For the cross section with polarized photons with E_{γ} = 41.2 to 93.0 MeV see (1988YO1A). For measurements in the Δresonance region see (1987KA13). The photoproduction of neutral pions (reaction (b)) has been studied from threshold to 450 MeV [see (1985AJ01)] and at E_{γ} = 132 to 169 MeV (1989KO05), 138 to 146 MeV (1986GL07, 1987GL01), 138.0 to 181.9 MeV (1987JA1F, 1987MA07) and 234 to 449 MeV (1986AR06). At E_{γ} = 157 to 170 MeV the excitation of ^{12}C*(4.4) is reported (1989PF1A; prelim.). See also (1989KO1Q) and (1984HO24, 1988ST12). For other papers on pion production (including π^{+} and π^{}) see the "General" section here, and ^{12}B and ^{12}N. For high energy processes see (1984AL1J, 1984AL1K). See also (1985AJ01), (1983AR24, 1983TO18, 1984ST18, 1986SH1M, 1988SC1B), (1985GI1G, 1985HO27, 1985MA1G, 1988OC1A), (1989BO1F; astrophysics) and (1984BO18, 1984CA18, 1985AL1K, 1985BO1A, 1985TO15, 1986HO11, 1987BE2A, 1987GOZK, 1987GO37, 1987KI1C, 1987PA1K, 1988AH03, 1988OR02; theor.).
Cross sections and angular distributions of the deuterons corresponding to transitions to ^{10}B_{g.s.} and/or low excited states have been measured at E_{γ} ≈ 40 MeV: the results are consistent with E2. There is some evidence also for the excitation of higher states of ^{10}B via nonE2 transitions. For E_{bs} = 90 MeV, the ratio of the yields of deuterons to protons is ≈ 2%, for particle energies 15 to 30 MeV. For higher particle energies, the ratio decreases: see (1980AJ01) for references. See also (1986SH1M). Momentum spectra for deuterons and tritons (reactions (a) and (d)) are reported at E_{γ} = 300 to 600 MeV by (1986BA07). The (γ, pn) reaction has been studied at E_{γ} = 83 to 133 MeV by (1988DA16) and in the Δresonance region by (1987KA13). For reaction (c) see (1987VO08). The yield of tritons has been measured for E_{γ} = 35 to 50 MeV: see (1980AJ01). See also (1985AJ01), (1984AL1J, 1984DO17) and (1985BU1H, 1986BU22, 1986GU1G, 1987BU1A; theor.).
The cross section exhibits broad peaks at about 18 MeV and ≈ 29 MeV; a pronounced minimum occurs at 20.5 MeV: to what extent the peaks have fine structure is not clear. For E_{γ} < 22 MeV, transitions are mainly to ^{8}Be(g.s.) and ^{8}Be*(2.9) with the g.s. transition dominating for E_{γ} ≲ 14 MeV. For E_{γ} > 26.4 MeV, ^{8}Be (T = 1) levels near 17 MeV are strongly excited. Surprisingly strong E1 contributions are observed below E_{γ} ≈ 17 MeV: see (1980AJ01) for references. See also (1986LI22). The ratio for σ(γ, α_{0})/σ(γ, p_{0}) is 0.029 ± 0.012 at E_{γ} = 28 MeV (1989FE01). For other breakup processes see (1975AJ02, 1985AJ01). See also (1985CH27; theor.).
Resonance scattering and absorption by ^{12}C*(15.11) have been studied by many groups: see (1980AJ01) and 12.7 (in PDF or PS) here. Inelastic scattering has also been reported to ^{12}C*(4.4, 9.6 ± 0.2, 11.8 ± 0.2, 12.7, 13.3 ± 0.2, 17.2 ± 0.2, 18.3 ± 0.2, 20.5 ± 0.2, 22  24 (giant resonance), 26.5 ± 0.4, 29.5 ± 0.3): see (1980AJ01, 1985AJ01). Measurements of the elastic differential cross sections for E_{γ} = 22.5 to 52.0 MeV (θ = 45°, 90°, 135°) have been reported by (1985WR02). The difference between the (measured) energyintegrated values of σ_{γ} and the E1 part of the photoabsorption cross section σ^{E1}_{γ} is small and cannot be ascribed to E2 strength (1985WR02). Beyond E_{γ} = 52 MeV significant E2 strength may be present (1985WR02). For the earlier work see (1985AJ01). See also (1984NA18, 1986BEZM), (1984NA1J, 1985HA1H, 1985MU08) and (1984MA1W, 1985AR07, 1985VE09, 1987FE05, 1987VE03; theor.).
Recent values of the nuclear charge radius are < r^{2} > ^{1/2} = 2.472 ± 0.015 fm, 2.464 ± 0.012 fm [2.468 ± 0.012 fm when the dispersion correction is made]: see (1985AJ01). A value obtained from muonic Xrays is displayed in the "General" section here. Elastic scattering has been studied up to 4 GeV: see (1968AJ02, 1975AJ02, 1985AJ01). (1986OF01, 1987OF1A) report evidence for an energy dependence of the elastic form factors, probably due to twostep processes, between E_{e} = 238 and 431 MeV. ^{12}C states observed in inelastic scattering are displayed in 12.15 (in PDF or PS). The variation of the form factor with momentum transfer yields unambiguous assignments of J^{π} = 2^{+}, 0^{+}, and 3^{} for ^{12}C*(4.4, 7.7, 9.6). Longitudinal form factors show ^{12}C*(16.1, 18.6, 20.0, 21.6, 22.0, 23.8, 25.5) while the transverse form factors show ^{12}C*(15.1, 16.1, 16.6, 18.1, 19.3, 19.6, 20.6, 22.7, (25.5)). ^{12}C*(19.4) may be the expected giant magnetic quadrupole state, J^{π} = 2^{}: see (1975AJ02, 1980AJ01) for references and additional information. The more recent work by (1984HI06, 1987HI09) is also displayed in 12.15 (in PDF or PS). A study of the (e, e'γ) reaction by (1985PA01) shows that the relative phase of the longitudinal and transverse form factors of ^{12}C*(4.4) is negative. Studies of the excitation of the Δresonance are reported by (1987OC01; E_{e} = 537 and 737 MeV) and by (1988BA25; E_{e} = 653, 1300, 1500, and 1650 MeV). See also (1986OLZY, 1986TH1F, 1987GI1G). See also (1985AJ01), reaction 35, (1984BU1H, 1984DE1P, 1985BU09, 1987KU05, 1988KO21), (1984HE1F, 1984LI25, 1985HI04, 1985PA1N, 1986HI06, 1986LI1C, 1986PA1C, 1987BE25, 1987DE43, 1987FR1B, 1987HO1D, 1987LI30, 1987RA1O) and (1983NA1E, 1984CA22, 1984CE05, 1984CI1A, 1984DE51, 1984DO14, 1984ER06, 1984KA1G, 1984KR10, 1984KU1E, 1984MO13, 1984RA1H, 1984RA14, 1984RO15, 1984SA1H, 1985BO06, 1985CE09, 1985CH07, 1985FR08, 1985KE1F, 1985KO06, 1985ME1L, 1985MU1F, 1985SA06, 1985SH1L, 1985ST09, 1986AZ01, 1986CZ01, 1986KO30, 1986KU09, 1986MAZF, 1986MU14, 1986PE1E, 1986SA2L, 1986SH01, 1986TR04, 1986ZE1A, 1987AL05, 1987AL1M, 1987CO30, 1987DO12, 1987DR02, 1987FE05, 1987FUZZ, 1987GM03, 1987JI01, 1987RA25, 1987SC26, 1987VOZS, 1988BE01, 1988CA20, 1988CH37, 1988CL03, 1988GU03, 1988GU12, 1988NI08, 1988PA25, 1988TR04, 1989LI1G, 1989MA06, 1989MI1I, 1989OR05; theor.).
I am extremely indebted to Dr. Larry Weinstein for his detailed comments which led to the writeup below. The inclusive studies by (1983BA28, 1984AR02, 1984OC01) uncovered a lack of understanding of the quasielastic and dip region processes. The more recent studies have focused on (a) quasielastic processes involving various states of ^{11}B [see ^{11}B and (1985VA05, 1985VA16, 1988VA09, 1988VA21)]; (b) quasielastic reaction mechanism studies including longitudinal/transverse separations (1986VA17, 1987UL03, 1988VA09, 1988WE1E); (c) dip and Δregion reaction mechanism studies (1986LO03, 1989BA03, 1989SE02); and (d) quasifree deuteron knockout spectroscopy to lowlying states of ^{10}B (1989EN01). See also (1987DA20, 1988AV01). Nuclear spectroscopy studies produce momentum distributions that are well reproduced by DWIA calculations but with occupation numbers that are about 60% of the expected shellmodel results (1985VA05, 1985VA16, 1988VA09, 1988VA21, 1987UL03, 1988WE1E). Studies of the quasielastic longitudinal and transverse response functions versus missing energy have been carried out by (1986VA17, 1987UL03, 1988VA09). See also (1988VA1I, 1988VA1J). (1987UL03) find in the longitudinal response a broad bump at missing energies between 28 and 48 MeV, attributed to knockout from the sshell. In the transverse response they find this bump on top of a broader feature with a threshold at 28 MeV extending beyond 65 MeV. This broad feature is attributed to twoparticle knockout, a nonquasielastic reaction mechanism; it may account for the observed (e, e') transverselongitudinal difference. This feature is also observed in unseparated data at larger momentum transfers: it appears to grow with momentum transfer (1988WE1E). (1984CA34) find evidence from the (e, ep_{0}) work for a monopole, 0^{+}, state near E_{x} ≈ 20.5 MeV which exhausts at least 1% of the EWSR. The decay of states in the giant resonance region via αparticles has been studied by (1987DEZU): the decay is primarily to ^{8}Be*(2.9) (J^{π} = 2^{+}). See also (1984FL02, 1986LI22). For other charged particle emission see (1984FL02). For pion emission see the "General" section here, ^{12}B, ^{12}N and (1986SH14, 1988SH36). For the early work see (1980AJ01, 1985AJ01). See also reactions 27 and 28, 1983BU20, 1984BU18, 1984LI07, 1985LI15, 1986BA85, 1987CAZY, 1987VA1N, 1988BA1D, 1988BOZT, 1988GAZV, 1989BOZZ), (1984LA16, 1984WA1J, 1985BE1K, 1986DE1T, 1986DE1U, 1986DO1N, 1986LA1T, 1987RI1A, 1988HA12) and (1983NA1E, 1984CA22, 1984CI1B, 1984HA1K, 1984NA16, 1984ZI1C, 1985AF03, 1985CA32, 1985CO14, 1985DE20, 1985DO1G, 1985KE1G, 1985LA1F, 1986AK01, 1986CO1U, 1986DE05, 1986GO1T, 1986NI03, 1986RO24, 1986RO22, 1986ST05, 1987AL19, 1987BL10, 1987BO54, 1987CH10, 1987GI07, 1987GOZO, 1987GU21, 1987MO1J, 1987MO24, 1987MO1M, 1987PA1J, 1987ST02, 1987VA15, 1987WE02, 1987YO04, 1988ER05, 1988HO09, 1988HO10, 1988KO13, 1988OC01, 1988SU02, 1988WE03, 1989BR01, 1989HO02, 1989PIZZ, 1989RY03, 1989TA03, 1989TA02, 1989WE1G; theor.).
Angular distributions of the elastic and inelastically scattered pions have been measured at many energies: see 12.16 (in PDF or PS) in (1985AJ01) and 12.16 (in PDF or PS) here. The study by (1987CO17) [E_{π±} = 100 to 291 MeV] suggests J^{π} = 2^{} for ^{12}C*(18.25, 19.4) and 4^{} for ^{12}C*(19.25). ^{12}C*(19.65) is also populated. A study of the giant resonance region suggests states at E_{x} = 20.0 ± 0.2 and 22.7 ± 0.4 MeV, with Γ = 3.2 ± 0.3 and 1.0 ± 0.2 MeV (1984BL12; E_{π+} = 170 MeV). The ratio of the cross sections to the 1^{+}; T = 0 and 1^{+}; T = 1 states, ^{12}C*(12.7, 15.1), has been measured at E_{π±} = 50 MeV, where it is 7.1 ± 1 [isospin averaged] (1988RI03). The excitation of these two states has also been studied for E_{π±} = 80 to 295 MeV by (1988OA03). See also (1988BA27). (1986AN01) have reported inelastic cross sections, including those to the "continuum" above ^{12}C*(9.6) at E_{π+} = 67, 85 and 100 MeV. The elastic excitation function at θ = 175° has been measured for E_{π+} = 100 to 250 MeV (1987DH01). Total reaction cross sections are reported at E_{π±} = 50 and 65 MeV (1987ME12). See also (1987BE1R). (π', γ_{4.4}) angular correlations have been studied at E_{π+} = 65 and 90 MeV (1984SO12) and 116 to 226 MeV (1986OL07, 1988OL02). See also (1985KI05). The (π', γ_{15.1}) angular correlations are reported at E_{π+} = 116 to 226 MeV (1988BA27). For reaction (b) see ^{11}B and (1984FA11; E_{π±} = 220 MeV) and (1987HU02; E_{π+} = 150 MeV). The polarization of protons in the π^{±} A → px process has been studied at 1.5 GeV/c (1984BU11). For studies of (π^{±}, 2p), (π^{+}, pd), and (π^{±}, pn) reactions see (1986AL22, 1986NA03, 1987YO01, 1989YO03). For the (π^{+}, 3p) reaction see (1985TA14, 1987BR17). See also the "General" section here, (1985AJ01) for the earlier work, (1984GO1F, 1989ROZZ), (1984KI16, 1985MI16) and (1985CO03, 1985KA04, 1986PE1E, 1986TA08, 1988ST07; theor.).
At E_{K±} = 442 MeV angular distributions have been obtained for ^{12}C*(0, 4.4, 9.6) (1982MA16). See also the "General" section here, (1988AF02) and (1988BR16; theor.).
Angular distributions of elastic and inelastically scattered neutrons have been studied at many energies up to 350 MeV [see (1980AJ01, 1985AJ01)] and at E_{n} = 11.05 and 13.81 MeV (1986HOZY; prelim.; n_{0}, n_{1}), 14.1 and 14.5 MeV (1983HU14; n_{0}, n_{1}), 14.6 MeV (1985HA02; n_{0}), 18.2 MeV (n_{0}; quoted in (1987TO03)), 20.8, 22, 24 and 26 MeV (1985ME16; to ^{12}C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 13.4, 14.1, 15.1, 16.1 [the latter two at E_{n} = 22 and 24 MeV (A.S. Meigooni, Ph.D. Thesis, Ohio University (1984) and R.W. Finlay, private communication)]) and 40.3 MeV (1986WI01; n_{0}). See also (1985FI09) and (1985PE10; theor.). For cross sections and polarization studies see (1985TO02, 1987TO07, 1987TO03, 1988TO01) and ^{13}C in (1991AJ01). Angular correlations (n_{1}, γ_{4.4}) have been studied at E_{n} = 13.9 to 15 MeV: see (1975AJ02). The quadrupole deformation parameter β_{2} = 0.67 ± 0.04 (1983WO02). For a kinematically complete study of reaction (b) at E_{n} = 11 to 35 MeV see (1983AN02): the sequential decay via ^{12}C*(9.6) and ^{8}Be_{g.s.} is clearly observed at the higher energies. See also (1986AN22) and (1980AJ01). For pion production see (1988BU16). See also (1985MA68, 1985PE1C, 1985WE1D, 1986BO1M, 1986ZH1F, 1987NEZY, 1988WE06), (1985FIZW, 1985HO1J, 1986HAYU), (1986KE1H, 1988AN1F; applications) and (1983KO44, 1983SH1P, 1985AU1C, 1985BE59, 1985DI1B, 1985GU1D, 1985TI08, 1986AL1L, 1986IS1F, 1986LI16, 1986SH35, 1987KO1N, 1987WI16; theor.).
Angular distributions of elastically and inelastically scattered protons have been measured at many energies up to E_{p} = 1040 MeV: see 12.17 (in PDF or PS) here and (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01). 12.18 (in PDF or PS) displays the information on excited states of ^{12}C. A summary of the decay of some excited states is shown in 12.7 (in PDF or PS). The angular distributions have been analyzed by DWBA (and CCBA), DWIA, (including microscopic calculations) and DWTA (DW tmatrix approximation with densitydependent interactions). Microscopic DWIA calculations give good results for transitions which take place through the S = T = 1 part of the effective interaction and also gives a reasonable description of the S = T = 0 transition. However the mechanism for the excitation of ^{12}C*(12.71) (S = 1, T = 0) remains a puzzle. At E_{p} = 402 MeV the differential cross sections for ^{12}C*(12.7, 15.1) (J^{π} = 1^{+}) are very similar for large q. This may be due to the smallness of precursor effects [precursor to a pion condensate] (1981ES04). The spinflip probability (SFP) for the transition to ^{12}C*(4.4) has been measured for E_{p} = 15.9 to 41.1 MeV: two bumps appear at ≈ 20 and ≈ 29 MeV. It is suggested that the lower one is due to a substructure of the E1 giant dipole resonance while the upper one results from the E2 giant quadrupole resonance. The SFP has also been studied at E_{pol. p} = 24.1, 26.2, 28.7 MeV (to ^{12}C*(4.44)), at E_{p} = 42 MeV (to ^{12}C*(12.7)), at E_{pol. p} = 397 MeV (to ^{12}C*(9.6, 12.7, 15.1, 16.1)) [the SFP to ^{12}C*(9.6) is consistent with zero; the others exhibit large SFP at forward angles] and at E_{p} = 398, 597 and 698 MeV (to ^{12}C*(18.3, 19.4)). See also (1987GRZY; prelim.). (1980HO07) have measured the angular distribution of γrays from the decay of ^{12}C*(12.7, 15.1) at E_{p} = 21.5 to 27 MeV. Microscopic DW calculations were performed for the A_{0} and a_{2} coefficients from these and earlier data. The theoretical calculations underestimate A_{0} for energies below 35 MeV and are in agreement with the experimental A_{0} for higher energies. The calculations also predict significant difference in the a_{2} values for the transitions from ^{12}C*(12.7, 15.1), and these are observed (1980HO07). (pγ_{15.1}) angular correlations have been studied at E_{p} = 400 MeV by (1988HI12): the data are best described by a relativistic model of pnucleus scattering in the impulse approximation. See also (1986SH1X). A search for a shortlived neutral particle emitted in the decay of ^{12}C*(15.1) is reported by (1988DA01) [see for upper limits]. For polarization and yield measurements see ^{13}N in (1986AJ01, 1991AJ01) and (1988FE09, 1989CH08). For other ^{12}C + p interactions see reaction 39, here. For other work and for earlier references see reaction 40 in (1985AJ01). See also (1983AP1A, 1985WIZW, 1986BA2U, 1986LI1Q, 1986SA2F, 1986TRZZ, 1987RO1F, 1988HI03, 1988LYZZ, 1989OPZZ), (1984GA32, 1984TA1L, 1985BL22, 1985BR1G, 1985CA1B, 1985HO1J, 1985ME16, 1985PE10, 1985SH1C, 1986CA1N, 1986GL1G, 1986HA2K, 1986MC1K, 1987BR32, 1988BO1I), (1987LA11, 1988LE08, 1988SA1B; astrophysics), (1987KO1M, 1988BA2A; applications) and (1983KO44, 1983LY07, 1983ZA09, 1984AM07, 1984LI1J, 1984LI1M, 1984LO20, 1984PH02, 1984SH14, 1985AU1C, 1985BA1Z, 1985CL1B, 1985DA24, 1985EL04, 1985IN01, 1985IV1A, 1985IV1B, 1985PI09, 1985PI11, 1985SH1H, 1985SM06, 1985SP03, 1985TI06, 1985ZH07, 1986BA62, 1986BL03, 1986CO1V, 1986DEZK, 1986DI04, 1986ES01, 1986IN01, 1986IS1F, 1986JA18, 1986KA1Y, 1986LO1A, 1986MO12, 1986PE1E, 1986POZW, 1986SH01, 1986SH35, 1986VD01, 1986YA16, 1987BI20, 1987CUZZ, 1987DA1D, 1987KA1G, 1987LI01, 1987MO13, 1987MU05, 1987NA1H, 1987RO02, 1987SCZV, 1987WI16, 1987ZA1F, 1988BEYI, 1988DA07, 1988HO09, 1988HO1K, 1988NA04, 1988PI02, 1988PR06, 1989TA03, 1989TU1A; theor.).
Antiproton scattering angular distributions have been measured at E(pbar) = 46.7 and 179.7 MeV (1986LE13, 1984GA32; to ^{12}C*(0, 4.4, 9.6)). See also (1985JA1J; also at 30 MeV; Ph.D. thesis). ^{12}C*(7.7) and some other, unresolved, groups were also populated (1986LE13). Cross section measurements are also reported at 1.45 and 1.8 GeV/c (1984AF1A). The knockout (pbar, p) reaction has been studied at E(pbar) = 180 MeV (1985GA02) and 600 MeV/c (1987AS06): there is no evidence for narrow bound or resonant overline pnucleus states. For a polarization study see (1988MA48). For spectra of ^{3}He and αparticles see (1988MA44). See (1985AJ01) for the earlier work, the "General" section here and (1984DA20, 1985AM01, 1985DA24, 1985LI16, 1986KL01, 1987AD04, 1988IN01; theor.).
Recent work on reaction (a) has involved the distribution of protons [and of deuterons from reaction (c)] associated with backward energetic protons over a wide kinematical range (1985MI09; E_{p} = 800 MeV). Spectra from coincident proton emission from the continuum have been studied at E_{p} = 200 MeV by (1988CO02). At E_{p} = 156 MeV states at 18.4, 19.4, 20.6 and ≈ 22 MeV appear to be involved (1989TEZZ; prelim.). At 2.1 GeV (1984TR09) have searched for interactions between the incident protons and a fast dinucleon constituent inside C. For inclusive proton spectra see (1985SE15, 1988FO06). See also (1985HAZW, 500 MeV; prelim.). For reaction (a) see also ^{11}B and (1984VD01, 1985BE30, 1985DO16). For reaction (b) see ^{11}C and (1985BE30, 1985DO16). For reaction (c) [and for the (p, p^{3}He) reaction] see (1985DE17, 1984DE1F). See also (1984TR09). At E_{p} = 56.5 MeV reaction (d) proceeds primarily by sequential αdecay. ^{12}C*(22.2 ± 0.5, 26.3 ± 0.5) which subsequently decay to ^{8}Be_{g.s.} must therefore have natural parity and a significaant T = 0 admixture. ^{12}C*(19.7, 21.1, 26.3) decay to ^{8}Be*(2.9). These states must also have a T = 0 component. It is suggested that ^{12}C*(21.1) has unnatural parity. At E_{p} = 44.2 MeV ^{12}C*(12.7, 14.1, 21.6, 26.6) are observed in the angular correlation involving α_{0} and ^{12}C*(21.6, 24.1, 26.6) decay via α_{1} to ^{9}Be*(2.9) [suggesting 2^{+} for these states, assuming that only resolved states are involved]. For reaction (e) see (1984NA17). A search for a bound ppπ^{+} state is reported at E_{p} = 500 MeV by (1988FR1D, 1988FR1J; prelim.). For isobar production at 3.88 GeV/c see (1987NA11). For inclusive pion production at E_{p} = 330, 400, and 500 MeV see (1985DI01). See also (1988AB05). For K^{+} production see (1986AB07, 1988KO36). For η production see (1987BL1L). For other work at high energies see (1986AG1C, 1986CH2H, 1987AG04, 1987AL1J, 1987CH1K, 1987DE1L). For the earlier work see (1985AJ01). See also the "General" section here, (1986VO17, 1987AR1M, 1988AG1A, 1988BE2B, 1988CHZV), (1985KI1A, 1986BA2D, 1986CH1J, 1987VD1A, 1988LE1I, 1988MO1H, 1988NA1H) and (1983KA1A, 1984GU14, 1985BU04, 1985GA1A, 1985GA1B, 1985KO2C, 1985SM1D, 1986ER1A, 1986GO1U, 1986HO10, 1986OS08, 1986VD01, 1986ZH03, 1987HO1G, 1987HO08, 1987VD1B, 1988BA83, 1988DZ1A, 1988KU16, 1988VD1B, 1989TA03; theor.).
The angular distribution of elastically and inelastically scattered deuterons has been studied at many energies: see (1968AJ02) and 12.22 (in PDF or PS) in (1975AJ02), 12.17 (in PDF or PS) in (1980AJ01), 12.17 (in PDF or PS) in (1985AJ01) and 12.17 (in PDF or PS) here. In addition to wellknown states in ^{12}C such as ^{12}C*(4.4) [E_{x} = 4440.5 ± 1.1 keV] and ^{12}C*(12.7, 15.1) [see 12.10 (in PDF or PS) for chargedependent matrix element], the population of ^{12}C*((10.8 ± 0.2), (11.8 ± 0.2), 18.3 ± 0.3, 20.6 ± 0.3, 21.9 ± 0.3 (broad), ≈ 27 (broad)) is also reported. See (1980AJ01) for references and for additonal structures which have not been published. Calculated deformation parameters listed in (1980AJ01) are β_{2} = 0.48 ± 0.02 and 0.47 ± 0.05, and β_{3} = 0.35 ± 0.06. Reaction (b) has been studied at E_{d} = 5.0 to 9.85 MeV and at 56 MeV: see (1980AJ01, 1985AJ01). The breakup of deuterons on C has been investigated at 2.1 GeV (1989PU01). For reaction (c) see ^{8}Be in (1984AJ01). Energy spectra for the (d, 2p) reaction, with the two protons in the singlet (^{1}S_{0}) state, have been studied at E_{pol. d} = 650 MeV and 2 GeV [reaction (d)]: the reaction appears to proceed via a onestep process and therefore can be used to study isospinspin excitations. The Δexcitation is observed (1987EL08). For work at very high energies see (1987AG04, 1987AL1J, 1987AR1M, 1987AZ1C, 1988AG1A, 1988SI1B). For highenergy γproduction see (1988TA22). See also ^{14}N in (1986AJ01, 1991AJ01), (1986JA14) and (1984YA01, 1985GA1A, 1985GA1B, 1986IS1F, 1986KA1B, 1987AU1F, 1987SI10, 1988SI04, 1989TU1A; theor.).
Angular distributions of elastically scattered tritons have been determined at E_{t} = 1.0 to 20.0 MeV [see (1975AJ02) and 12.17 (in PDF or PS) in (1985AJ01)] and at 33 and 36 MeV (see 12.17 (in PDF or PS)). See also (1985SA31; theor.).
Angular distributions of ^{3}He ions have been measured for E(^{3}He) = 2 to 217 MeV: see (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01) and 12.17 (in PDF or PS) here. Parameters of observed ^{3}He groups are displayed in 12.19 (in PDF or PS). Angular distributions of the ^{3}He groups to ^{12}C*(15.11, 16.11, 16.57, 19.55) have been compared with those for the tritons to ^{12}N*(0, 0.96, 1.19, 4.25) in the analog (^{3}He, t) reaction: the correspondence is excellent and suggests strongly that these areT = 1 isobaric analog states. See also 12.12 (in PDF or PS) in (1980AJ01) and 12.19 (in PDF or PS) here. ^{12}C*(4.4, 15.2, 18.4, 18.9, 21.3, 23.5, 25.9, 28.8) all appear to correspond to E2 transitions: their strengths add up to 46% of the EWSR (energyweighted sum rule). See (1980AJ01) for references and (1985AJ01) for additional comments. For reaction (b) see (1985AJ01). Inclusive proton and deuteron spectra have been studied at E(^{3}He) = 52 MeV by (1984AA01). For reaction (c) see ^{13}C and ^{15}O in (1991AJ01) and (1986KA44). For π^{±} production see (1986MI25). See also ^{15}O in (1986AJ01, 1991AJ01), (1987AD1C), (1987MA2D) and (1985GO19, 1985KH08, 1985SH1A, 1986EV01, 1986EV02, 1986IS1F, 1986KA1B, 1986ZE04, 1987RA36, 1987TR01; theor.).
Angular distributions have been measured at many energies up to 1.37 GeV: see 12.24 (in PDF or PS) in (1968AJ02), 12.22 (in PDF or PS) in (1975AJ02), 12.17 (in PDF or PS) in (1980AJ01), 12.17 (in PDF or PS) in (1985AJ01) and 12.17 (in PDF or PS) here. Parameters of observed states of ^{12}C are displayed in 12.19 (in PDF or PS). The quadrupole deformation parameter β_{2} = 0.30 ± 0.02 [see (1980AJ01)], 0.40 ± 0.02 (1983YA01), while β_{3} ≈ 0.23 [see (1980AJ01)] and β_{4} = +0.16 ± 0.03 (1983YA01; see also for a review of deformation parameters). In the region of the GDR prominent gross structure is observed consisting of two ≈ 2 MeV wide peaks at 26.2 and 29.2 MeV (1987KI16; see also for a discussion of deformation parameters). Angular correlation measurements (α_{1}, γ_{4.4}) have been carried out for E_{α} = 10.2 to 104 MeV [see (1980AJ01, 1985AJ01)] and at 25 to 30 MeV (1984TE01, 1986GU06, 1986ZE1C; see for a study of the spin tensors for ^{12}C*(4.4)). Reaction (b) has been studied for E_{α} up to 700 MeV [see (1975AJ02, 1985AJ01)], at 27.2 MeV (1986KO1B; prelim.) and at 31.2 MeV (1986XI1A). For cross sections see ^{16}O in (1986AJ04) and (1987BU27). For other comments on these two reactions see (1985AJ01). For π^{±} emission see (1986ALZL, 1986ALZK, 1987AL1G; prelim.). For highenergy γproduction see (1988TA22). For work at very high energies see (1984AN1H, 1985AB1A, 1986BA3D, 1987AG04, 1987AL1J, 1987AR1M, 1988AG1A, 1988SI1B). See also (1984SA28, 1985XI1C, 1987GOZL, 1988AI1B, 1989ES06, 1989LE09), (1983SA07, 1985HO1J), (1988MU1G, 1989LA1G; astrophysics) and (1983AL1F, 1983GE10, 1983GO27, 1985GA1A, 1985GA1B, 1985KH08, 1985SA09, 1986SH1I, 1985ZE02, 1985ZE04, 1986BA11, 1986BE45, 1986EL08, 1986LI1U, 1987BA83, 1987CUZZ, 1987KA1G, 1987KH06, 1987KO1E, 1987KU18, 1987NO05, 1987SA55, 1987VOZS, 1987ZE02, 1988BA1Q, 1988GR1C, 1988KH08, 1988KU1D, 1988KUZU, 1988MA10, 1989TU1A; theor.).
Angular distributions in reactions (a) and (c) have been studied at E(^{6}Li) = 4.5 to 210 MeV and E(^{7}Li) = 4.5 to 131.8 MeV: see (1975AJ02, 1980AJ01, 1985AJ01) for the earlier work and 12.20 (in PDF or PS) here. See also (1989TRZZ). Reaction (b) takes place via ^{12}C*(0, 4.4, 7.7): see (1985AJ01, 1986AJ04) and (1985CU04). See also (1988AR22). For VAP measurements (reaction (a)) see (1989VA04; g.s., 4.4) and (1987TA21; g.s.). See also (1988TA08, 1989TRZZ) and ^{18}F in (1987AJ02). A search by (1987EY01) for the distribution of the E0 strength determines 10%, (5 ± 1)% and (5 ± 2)% of the EWSR, respectively for ^{12}C*(7.7, 10.3) and for 19 < E_{x} < 21.5 MeV. For fusion and other cross section measurements (reaction (a)) see (1987PA12). For the ^{6}Li and ^{7}Li + C interaction cross section at 790 MeV/A see (1985TA18). For pion emission see (1984BE35, 1984CH16). The elastic scattering in reaction (d) has been studied at E(^{7}Be) = 140 MeV (1989YA02). See also (1986DAZP, 1986SHZP, 1986YOZU), (1984HA53, 1986KA1C, 1986MO1E) and (1983DE48, 1983GO18, 1984MU1D, 1984UH1A, 1985CO21, 1985HE25, 1985KH08, 1985SA13, 1985SH1A, 1986BE45, 1986IO01, 1986KA1B, 1986MI24, 1986SA15, 1986SAZL, 1986SA1D, 1986YO1A, 1987AR13, 1987KA1I, 1987SA21, 1988DEZU, 1988KH08, 1988OT01, 1988SA10, 1988SA15, 1988SE07, 1989KAZY; theor.).
Angular distributions have been obtained at E(^{9}Be) = 14 to 158.3 MeV and at E(^{12}C) = 12 to 21 and 65 MeV: see 12.20 (in PDF or PS) here and (1980AJ01, 1985AJ01). For fusion and yield measurements see (1985AJ01) and (1985DE22). For the ^{9}Be + C interaction cross section at 790 MeV/A see (1985TA18). See also (1988HAZS), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A) and (1984HA43, 1986BA69, 1986HA13, 1986KA22, 1986MI24, 1988KH08; theor.).
Angular distributions in reaction (a) have been measured at E(^{10}B) = 18 and 100 MeV. Those for reaction (b) have been studied at E(^{11}B) = 10.4 to 100.0 MeV and E(^{12}C) = 15 to 87 MeV: see (1980AJ01, 1985AJ01) and 12.20 (in PDF or PS) here. For fusion and yield studies see (1985AJ01) and (1985MA10, 1986MA13). See also (1984DEZX, 1984HAZK, 1987SAZW, 1988SAZT). See also (1987PO15), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1986MA19, 1988MA07), (1982BA1D, 1985BA1T; astrophysics) and (1984HA43, 1984IN03, 1985KO1J, 1986BA69, 1986HA13, 1986RO12, 1988DI08; theor.).
Angular distributions have been measured at E(^{12}C) = 10 to 1020 MeV: see (1980AJ01, 1985AJ01) and 12.20 (in PDF or PS) here. Angular distributions of the magnetic substate population for the single and mutual ^{12}C*(4.4) excitation have been measured by (1985SU07) for E(^{12}C) = 38 to 110 MeV. The yields of 12.7 and 15.1 MeV γrays have been studied at E(^{12}C) = 180 MeV (1988HA23), and hard photon collisions have been investigated at E(^{12}C) = 576 to 1008 MeV (1986GR19). For other studies of excitation functions and reaction cross sections see (1984KO12, 1984SI15, 1985KO17, 1985KO24, 1985ME1K, 1985PA24, 1986HAZA, 1986HA30, 1986SA29, 1987HO11, 1987KO12, 1988DE18, 1988PA04, 1989LI10, 1989PA05). See also (1984HO1K). For a study of the effects of vacuum polarization in hadronhadron scattering see (1989VE03). For reaction (b) see (1986SH10, 1988CAZU) and ^{16}O in (1986AJ04): the excitation of ^{12}C*(9.6, 10.8, 14.1) is reported at E(^{12}C) = 90 to 140 MeV. For fragmentation studies see (1985HA1U, 1985KR03, 1986EN1D, 1986FO04, 1987FO08, 1988FO03, 1988KI05). See also (1985KR21, 1986LIZP, 1987PO15) and (1989CO1C, 1989HA43; theor.). For pion production see (1983AN1L, 1984AG1A, 1984BE35, 1984CH16, 1985AR1M, 1986AN40, 1988BA21, 1988NO09). See also (1985OB1A) and the "General" section here. For other studies at very high energies see (1984AD1C, 1984AD1B, 1984AN1H, 1985RO12, 1986AG1B, 1986AN1X, 1986CH2H, 1987AD1E, 1987AG04, 1987AG1A, 1987AL1J, 1987AN20, 1987AR1M, 1988AG1A, 1988SI1B). See also (1985GO1H, 1985SU16, 1985VI03, 1985XI1B, 1986BL1K, 1986BL1L, 1986CO02, 1988HAZS, 1988KW1B, 1988SAZT, 1989OG03), (1982CI1C, 1984BR1L, 1984FR1A, 1984GE1D, 1984HA53, 1984NA1D, 1984TA1L, 1984TR1E, 1985BE1A, 1985CU1A, 1985NA1B, 1986BA2D, 1986BE2H, 1986BE1D, 1986CA30, 1986DU1N, 1986GR1K, 1986SN1B, 1986ST1J, 1987BA1G, 1987BL1D, 1987BR1R, 1987GE1B, 1987HO1C, 1987SC1D, 1988BA12, 1988BE1W, 1988BO46, 1988CA1L, 1988HA1R, 1988RA1G, 1989BL1D), (1982BA1D, 1985BA1T, 1986MA44, 1987RO25, 1989KH02; astrophysics) and (1983SH1Q, 1984AI02, 1984CA28, 1984DA1M, 1984GA1G, 1984GA12, 1984HA43, 1984KA1H, 1984LA1L, 1984SH18, 1984TR14, 1984ZA1B, 1985AI1A, 1985AI1B, 1985AM1B, 1985BA42, 1985BA63, 1985BL09, 1985BL17, 1985BO1A, 1985CH03, 1985CS02, 1985GR1F, 1985GU1J, 1985HA1N, 1985HU04, 1985IV1B, 1985KA1W, 1985KA1X, 1985KH1E, 1985LA14, 1985LE25, 1985LI1K, 1985MA1L, 1985ME14, 1985ME15, 1985MR1A, 1985NO06, 1985PA1P, 1985SA1D, 1985SH1A, 1985TA07, 1985TA12, 1985TO01, 1985TO04, 1985UM01, 1985VA17, 1986AB1H, 1986BA01, 1986BA30, 1986BA1D, 1986BA62, 1986BL05, 1986CA26, 1986CO17, 1986CS1A, 1986CS01, 1986DE07, 1986DI1D, 1986FA1A, 1986GA1F, 1986GR1M, 1986GR1A, 1986HA1Z, 1986HA13, 1986HN01, 1986HO1P, 1986KA22, 1986KA1B, 1986KH04, 1986KI1L, 1986MA44, 1986NI01, 1986OR01, 1986PH01, 1986POZW, 1986PR1C, 1986PR01, 1986RE05, 1986RO26, 1986SA03, 1986SA30, 1986SA1D, 1986SH04, 1986ST1N, 1986VI07, 1986WU03, 1986YA1U, 1987AB1K, 1987AR13, 1987AS05, 1987BA2D, 1987BA50, 1987BI20, 1987BO45, 1987BO28, 1987DA1L, 1987DI1A, 1987FR06, 1987GU13, 1987KH06, 1987KU1B, 1987MA17, 1987MA1J, 1987MA2D, 1987OC1B, 1987OH02, 1987OH08, 1987OH09, 1987OH13, 1987PA24, 1987PH01, 1987RA28, 1987RE03, 1987RE11, 1987RE1G, 1987SC33, 1987ST1E, 1987YA1L, 1988AB1E, 1988AB1F, 1988AD1C, 1988AI1D, 1988AS03, 1988BA04, 1988BA2X, 1988BA43, 1988BA37, 1988BO21, 1988BR04, 1988BR20, 1988BR29, 1988CA08, 1988DE39, 1988DJ1A, 1988FR14, 1988GA1C, 1988GAZW, 1988HE12, 1988IW02, 1988KA1S, 1988KH07, 1988KH09, 1988KH1B, 1988KHZX, 1988LE20, 1988MA10, 1988NA10, 1988OH01, 1988OH09, 1988PO06, 1988PR02, 1988PR04, 1988SE1D, 1988TO02, 1988WU1A, 1988ZU01, 1988ZW1A, 1989EL01, 1989MR01, 1989SH05, 1989TU1A; theor.).
Angular distributions for reaction (a) have been studied at E(^{12}C) = 15 to 87 MeV and E(^{13}C) = 12, 36 and 87 MeV [see (1975AJ02, 1985AJ01)] and at E(^{12}C) = 94.5 MeV (1986BA80; g.s.) and E(^{13}C) = 16.3 to 20.6 MeV (1984FR05; g.s.), 17.3 to 26.5 MeV (1988VO01; g.s.), 36 MeV (1985BY01; ^{12}C*(4.4)) and 260 MeV (1985BO39; ^{12}C*(0, 4.4)). Elastic angular distributions (reaction (b)) are reported at E(^{12}C) = 12 to 20 MeV [see (1980AJ01)] and at E(^{14}C) = 31.0 to 56 MeV (1985KO04). The spinflip probability to ^{12}C*(4.4) has been studied at E(^{13}C) = 36 and 56 MeV by (1985BY01). See (1985AJ01) for the earlier work. For yield and cross section measurements see (1985KO04, 1985RI1C, 1986HA30, 1986STZY, 1987KO12) and (1985AJ01). See also ^{13}C and ^{14}C in (1991AJ01), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1986SN1B, 1987IM1C, 1988BE1W, 1988JA14, 1989VO1D), (1982BA1D, 1985BA1T; astrophysics) and (1983HU1C, 1984IN03, 1984SA31, 1984VO11, 1985HU04, 1985IM1B, 1985KO1J, 1985SA1D, 1985VO01, 1986BA1D, 1986BA69, 1986EL02, 1986HA13, 1986KA1B, 1986SA1D, 1986VI08, 1987AR1E, 1987BO48, 1987FR06, 1987IM01, 1987KAZK, 1987MA22, 1988BR29, 1988KA27, 1988PA07; theor.).
Angular distributions (reaction (a)) have been measured at E(^{14}N) = 21 to 155 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)] and at E(^{14}N) = 150 MeV (1986GO1H; prelim.). Angular distributions for reaction (b) are reported at E(^{15}N) = 31.5 to 94 MeV: see (1980AJ01, 1985AJ01). Highenergy γray emission has been studied at E(^{14}N) = 280 to 560 MeV (1986ST07). See also (1987ST1F). For yield, fragmentation and crosssection measurements see (1985AJ01) and (1985CA01, 1986HA1F, 1986MO13, 1987GO01, 1987ST01, 1988KI06). For the ^{12}C(^{14}N, d^{12}C)^{12}C reaction see (1985ARZW, 1986AR1G; prelim.). See also ^{14}N and ^{15}N in (1991AJ01), (1987VE1D, 1988HAZS), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1987GE1B, 1989BL1D), (1982BA1D, 1985BA1T; astrophysics) and (1984HA43, 1985HU04, 1985KO1J, 1985VI09, 1986BA62, 1986BA69, 1986HA13, 1986POZW, 1986RE14, 1987BI20, 1987RE03, 1987RE11, 1988BA2X, 1988BA37, 1988HE12, 1988PR02, 1989SH05; theor.).
Angular distributions have been measured at E(^{16}O) = 17.3 to 1503 MeV and at E(^{12}C) = 65 to 76.8 MeV: see (1975AJ02, 1980AJ01, 1985AJ01) and 12.20 (in PDF or PS) here. The excitation of ^{12}C*(0, 4.4, 14.1, 26) has been reported. The latter is due to the wide (Γ ≈ 4 MeV) giant quadrupole resonance. It contains 25^{+15}_{10}% of the E2 strength: see (1985AJ01). For fusion, yield, crosssection and fragmentation studies see (1985AJ01) and (1984TS07, 1985BE02, 1985BE40, 1985CA01, 1985KA03, 1985MU18, 1986CH27, 1986CH41, 1986GA13, 1986HA30, 1986IK03, 1987SU03, 1988KO17). See also (1984RU1A, 1987NA1C, 1988SZ02, 1989KRZX, 1989WE1E). For work at very high energies see (1987YO1A). See also ^{16}O in (1986AJ04), (1988CAZV, 1988HAZS), (1982CI1C, 1984GE1D, 1984HA53, 1984SN01, 1984TR1E, 1985BE1A, 1985CU1A, 1985GA1J, 1985KA1J, 1985SN1A, 1986RE1A, 1986SN1B, 1987BA1G, 1987BO1H, 1987HO1C, 1988RA1G, 1989CI1C, 1989ST1G), (1982BA1D, 1985BA1T; astrophysics) and (1983HU1C, 1984FR1A, 1984HA43, 1984IN03, 1984KA1H, 1984LA1L, 1984SA31, 1985AI1A, 1985BA63, 1985HU04, 1985HU1C, 1985KA1X, 1985KA28, 1985KO1J, 1985ME14, 1985NO1E, 1985SA1D, 1985TR1D, 1985VI09, 1986BA1D, 1986CH44, 1986DE15, 1986DE40, 1986HA13, 1986KA1B, 1986KL06, 1986POZW, 1986SA1D, 1986WU03, 1987AR13, 1987BA50, 1987DA02, 1987PA24, 1987SC33, 1988AB1E, 1988AB1F, 1988BA43, 1988BR04, 1988BR20, 1988BR29, 1988FR14, 1988JI02, 1988KA13, 1988KO27, 1988SE1D, 1989EL01, 1989MA25; theor.).
The elastic scattering angular distributions have been studied at E(^{17}O) = 30.5 to 35 MeV and at E(^{18}O) = 32.0 to 140 MeV [see (1980AJ01, 1985AJ01)] and at E(^{17}O) = 40 to 70 MeV (1986FR04). For fusion, yields, and crosssection measurements see (1985BE40, 1985BE37, 1985CA01, 1986FR04, 1986GA13) and (1985AJ01). For the decay of ^{18}O* into ^{14}C + α, see reaction 34 in ^{18}O (1987AJ02). See also (1984FR1A, 1984HA53, 1989CI1C, 1989FR04), and (1986CI01, 1986HA13, 1987AR1E, 1987MO27, 1987VO05, 1988TH02, 1988THZZ; theor.).
Angular distributions have been measured at E(^{12}C) = 30.0, 40.3, 50.0 and 60.1 MeV and at E(^{19}F) = 40, 60, and 68.8 MeV [see (1980AJ01, 1985AJ01)] as well as at E(^{19}F) = 29.3 to 34.8 MeV (1984MA32; elastic) and E(^{12}C) = 30.0, 40.3, 50.0 and 60.1 MeV (1988TA12; ^{12}C*(0, 4.4) and several states in ^{19}F). The substate population probability for ^{12}C*(4.4) has been studied by (1986IKZZ) at E(^{19}F) = 63.8 MeV. For fusion and yield measurements see (1985AJ01) and (1984MA32, 1986GA13, 1986VO12). For the αdecay of ^{19}F* see reaction 42 in ^{19}F in (1987AJ02) and (1985SM04). See also (1986MA1Z), (1984FR1A, 1984HA53) and (1985HU04, 1986HA13, 1986HE1A, 1987CO01, 1988DI08; theor.).
Elastic angular distributions (reaction (a)) have been measured at E(^{12}C) = 20 to 77.4 MeV and at E(^{20}Ne) = 65.7 MeV: see (1980AJ01, 1985AJ01). For fusion, reaction cross section, yield and evaporation residue studies see (1985AJ01) and (1984KO12, 1984RA10, 1985MU18, 1985OS05, 1987KO12, 1987SI06). See also (1985FL1B). For pion production see (1985AJ01) and (1983AN1L). For other work at very high energies see (1984AN1H, 1987AN20, 1988DU01). See also (1983AN1K, 1986BL1K), (1984FR1A, 1984HA53, 1984NA1D, 1984ST1B, 1985BE1A, 1985CU1A, 1985ST1B, 1986IK03, 1986ST1J, 1987LA05, 1987SC1D, 1988BO46, 1989CI1C) and (1984HA43, 1984IN03, 1984SH1T, 1985CH11, 1985GA1G, 1985GU1J, 1985HU04, 1985KO1J, 1986GA1F, 1986GI03, 1986HA13, 1986HE1A, 1987SC33, 1988IW02; theor.).
Elastic angular distributions have been measured at E(^{12}C) = 20 to 60 MeV (reaction (a)) and at E(^{12}C) = 20 to 56 MeV (reaction (b)): see (1985AJ01). For fusion, yields and crosssection measurements see (1985AJ01) and (1986GL03, 1988DU11). The fission of ^{24}Mg into 2 ^{12}C (involving ^{12}C*(0, 4.4)) has been studied by (1986FUZW; prelim.). See also (1982CI1C, 1982ME1A, 1984FR1A, 1984HA53, 1986BE1D, 1987KA2A, 1987LA05, 1988RA1G, 1989CI1C) and (1985AN16, 1985LE25, 1986BO14, 1986HA13, 1987BR1H, 1987GR04, 1988AY03, 1988KU1H; theor.).
Angular distributions have been measured at E(^{12}C) = 30.0 to 39.9 MeV and at 82 MeV: see (1985AJ01). For fusion, yield, and breakup measurements see (1985AJ01) and (1984KO12, 1985HA19, 1987KO12). See also (1987PO15). For work at very high energies see (1986AN1X). See also (1985XI1B, 1986BL1L), (1984FR1A, 1986CA30, 1988SN1A) and (1984FO21, 1984NA27, 1986POZW, 1986RO12, 1987ST1E, 1988TO02, 1989SH05; theor.).
Elastic angular distributions have been studied for reaction (a) at E(^{12}C) = 19 to 186.4 MeV and at E(^{28}Si) = 58.3 to 116.7 MeV [see (1980AJ01, 1985AJ01)] as well as at E(^{12}C) = 56, 59, 66 and 69.5 MeV (1985SH1K) and 65 MeV (1988YA06). Alphaγ angular correlations have been studied at E(^{28}Si) = 112.3 and 142.7 MeV: ^{12}C*(4.4) is found to be produced almost entirely in the m= 0 magnetic substate (1986RA08). For fusion, yield and breakup measurements see (1985AJ01) and (1984SH19, 1986HA33, 1987ZH1G). See also (1985SAZZ, 1986FEZY, 1986HAZS, 1987SHZY, 1988MAZZ). For pion production see (1983AN1L). For other work at very high energies see (1987AN20). See also (1988SA1S, 1988SH33), (1982CI1C, 1984FR1A, 1984HA53, 1986BE2H, 1987LA05, 1989CI1C) and (1986GR1A, 1986KUZZ, 1987AR13, 1987BR1A, 1987KI12, 1987SH06, 1988AL06, 1988AY03, 1988KU1G, 1988KU1H; theor.).
Elastic angular distributions are reported at E(^{12}C) = 35.8 MeV and E(^{32}S) = 73.3 to 160 MeV [see (1980AJ01, 1985AJ01)] as well as E(^{32}S) = 194, 239 and 278 MeV (1987HI10). For fusion, yield and evaporation residue studies see (1985AJ01) and (1985KO21, 1986PL02, 1987HI10, 1988AR21). See also (1987LA05) and (1989CI1C).
Elastic angular distributions (reaction (a)) have been studied at E(^{12}C) = 54 and 63 MeV: see (1985AJ01). For reaction (b) see (1989PL02) and (1985MO1K; prelim.).
The elastic scattering in all three reactions has been studied at E(^{12}C) = 51.0, 49.9 and 49.9 MeV, respectively [see (1985AJ01)] and, for reaction (a), at E(^{12}C) = 180, 300 and 420 MeV (1986SA29). For fusion, yield, crosssection and fragmentation studies see (1980AJ01, 1985AJ01) and (1984GR20, 1984KO12, 1986SA29, 1987KO12). See also (1985XI1B), (1989BE17, 1989GR04) and (1984SH1T, 1985BL18, 1986CH20, 1986CH38; theor.).
The decay is mainly to the ground state via an allowed transition. Branching ratios to other states of ^{12}C are displayed in 12.21 (in PDF or PS). The halflife of ^{12}N is 11.000 ± 0.016 ms (1978AL01). See also (1968AJ02). The ratio of the branching ratios ^{12}N/^{12}B for the decays to ^{12}C*(4.4) is 1.528 ± 0.027 (1988NA09). See also (1985AJ01). This leads to the following values for the mirror asymmetries of ^{12}B and ^{12}N for decay to ^{12}C*(0, 4.4): δ_{g.s.} = +0.129 ± 0.008 (1978AL01), δ_{4.4} = +0.066 ± 0.018 (1988NA09). See also (1989KR1C).
The decay of the giant resonance in ^{13}C takes place predominantly to ^{12}C*(15.1, 16.1) [and to their analogs in ^{12}B]. Below E_{γ} = 21 MeV transitions to ^{12}C*(4.4) are dominant: see (1980AJ01). See also ^{13}C in (1991AJ01).
Angular distributions (reaction (a)) have been measured at E_{π+} = 90 to 170 MeV to ^{12}C*(0, 4.4, 7.7, 9.6, 12.7, 14.1, 15.1, 16.1, 19.1, 20.6, 22.9, 25.3): an energy dependent ratio for the excitation of ^{12}C*(12.7, 15.1) is reported. Similarities in the population of states seen in this reaction and in the (p, d) reaction are observed. Angular distributions at E_{π+} = 32 MeV are also reported: see (1985AJ01). For reaction (b) see (1988POZV).
Angular distributions have been measured at E_{p} = 8 to 800 MeV [see (1980AJ01, 1985AJ01)], at E_{p} = 18.6 MeV (1986GO23, 1987GO27; ^{12}C*(0, 4.4)), 41.5 MeV (1987CA20; ^{12}C*(0, 4.4, 12.7, 15.1, 16.1)) and 800 MeV (1984SM04; ^{12}C*(0, 4.4, 12.7, 14.1, 15.1, 16.1)) and at E_{pol. p} = 119 MeV (1987LE24; ^{12}C*(0, 4.4, 7.7, 9.6, 12.7, 14.1, 15.1, 16.1, 16.6, 17.8, 18.16 ± 0.07, 18.8, 19.9, 20.3, 20.6)) and 500 MeV (1984OH06; g.s.). The population of ^{12}C*(10.3, 15.4) is also reported, and the Γ_{c.m.} of the structures at E_{x} = 18.2, 18.8, 19.9, 20.3 and 20.6 MeV are, respectively, 240 ± 50, 120 ± 30, ≈ 400, ≈ 220 and ≈ 210 keV (1987LE24). (1984SM04) report structures at 20.61 ± 0.04 and 25.4 ± 0.1 MeV, the latter with Γ ≥ 0.5 MeV. The earlier work [see (1980AJ01)] indicated states at 17.76 ± 0.02 [80 ± 20], 18.80 ± 0.04 [80 ± 30], 21.5 ± 0.2 [< 200] and 22.55 ± 0.05 [< 200] MeV [the numbers shown in brackets are Γ_{c.m.}, in keV]. For (d, γ) correlations via ^{12}C*(15.1) see (1987CA20). See also ^{14}N in (1991AJ01), (1987GIZZ, 1988LE08) and (1988BE1I, 1988GUZW; theor.).
Angular distributions have been studied at E_{d} = 0.41 to 27.5 MeV [see (1975AJ02, 1980AJ01)] and 18 MeV (1988GO02, 1988GU20; t_{0}, t_{1}) as well as E_{pol. d} = 29 MeV [to ^{12}C*(0, 4.4, 12.7, 15.1, 16.1)]: see (1985AJ01). For chargedependent matrix elements between ^{12}C*(12.7, 15.1) see 12.10 (in PDF or PS). See also (1986GU1J; applications) and (1988GUZW; theor.).
Angular distributions have been measured at many energies up to E(^{3}He) = 45 MeV [see (1980AJ01, 1985AJ01)] and at 22.7 MeV (1987VA1I; α_{0}, α_{1}; prelim.). See (1984VA39, 1985VA1E, 1986ZE1C) for a study of the spin tensors for ^{12}C*(4.4). A study of reaction (b) leads to Γ_{α}/Γ for ^{12}C*(15.11) = (4.1 ± 0.9)%; together with the other parameters for the decay of the state (see 12.7 (in PDF or PS)) this leads to Γ_{α} = 1.8 ± 0.3 eV. If this isospinforbidden αwidth is the result of mixing between ^{12}C*(12.71, 15.11) via a chargedependent interaction the matrix element is 340 ± 60 keV: see, however, 12.10 (in PDF or PS) here, and (1980AJ01). See also (1987BA2B, 1987ZE02, 1988GOZB; theor.) and ^{16}O in (1986AJ04).
See ^{13}C in (1991AJ01) and (1984DE44, 1985DE1Q).
At E(^{7}Li) = 34 MeV angular distributions have been observed for the reactions to ^{12}C*(0, 4.4) + ^{7}Li*(g.s., 0.48) and ^{8}Li*(0, 0.95) in all combinations. While ^{12}C*(0, 4.4) are dominant in the two spectra, ^{12}C*(7.7, 9.6) and, in reaction (a) at E(^{6}Li) = 36 MeV, ^{12}C*(12.7), are also populated: see (1980AJ01) and (1987CO16; reaction (b)).
Angular distributions have been reported for reaction (a) at E(^{13}C) = 16.0 to 50.0 MeV : (see (1985AJ01) [also excitation functions]) and at E(^{13}C) = 20.0 to 27.5 MeV (1988BI11) for reaction (b). See also (1984BA31) and (1987TH04; theor.). For reaction (c) see (1989FR04). See also (1980AJ01).
See ^{14}C in (1991AJ01), (1985PY01) and (1987GO09; theor.).
Angular distributions have been measured at E_{p} = 14.5, 18.5, and 39.8 MeV: see (1975AJ02). At E_{p} = 54 MeV angular distributions are reported to two states at E_{x} = 27.57 ± 0.03 and 29.63 ± 0.05 MeV [Γ_{c.m.} ≲ 200 keV]: their identification as the first T = 2 states is supported by the similar angular distributions to the first two T = 2 states in ^{12}B, reached in the (p, ^{3}He) reaction [see reaction 28 in ^{12}B]. The lower T = 2 state is well fitted by L = 0; the angular distribution to ^{12}C*(29.63) is rather featureless. It is suggested that its shape is somewhat more consistent with L = 0 than with L = 2 (1976AS01): [(1976BA24) has suggested that the second T = 2 state in A = 12 may have J^{π} = 0^{+}.] It is not excluded that the group to ^{12}C*(29.63) may be due to unresolved states (1976AS01). (1976AS01) report Γ_{p}/Γ ≈ 0.3 ± 0.1 and Γ_{α1}/Γ < 0.1 for the first T = 2 state and Γ_{p}/Γ = 0.8 ± 0.2, Γ_{p0}/Γ ≈ 0.4 and Γ_{α}/Γ ≈ 0.2 for ^{12}C*(29.63). (1978RO08) report E_{x} = 27595.0 ± 2.4 keV, Γ ≤ 30 keV for the first T = 2 state and calculate the decay properties for two values of the total width, 0 and 30 keV. Branching ratios for the decays to ^{8}Be(0) + α; ^{11}B*(0, 2.12, 4.45, 5.02, 6.74 + 6.79) + p; and ^{10}B(0) + d are, repectively, (10.5 ± 3.0)%; (3.0 ± 2.2)%, (8.0 ± 2.3)%, (0 ± 3.3)%, (8.4 ± 3.2)%, (8 ± 5)%; and (2.8 ± 2.0)% (1979FR04).
Angular distributions (reaction (a)) have been studied at E_{p} = 7.5 to 52 MeV [at the higher energies to ^{12}C*(12.7, 14.1, 15.1, 16.1)] as well as to ^{12}C*(0, 4.4): see (1980AJ01). For reaction (b) see (1985DE17) and (1986VDZY). See also (1987VD03, 1987VD1A) and (1986GO28; theor.).
Observed αparticle groups are displayed in 12.19 (in PDF or PS). Angular distributions have been measured at energies up to 40 MeV: see (1980AJ01) [also for J^{π} assignments]. See also (1987SI1D; applications), (1983US01; theor.) and ^{16}O in (1986AJ04).
See (1988SH1E; theor.).
See (1986GO1B).
See (1987AR25) and ^{14}N in (1991AJ01).
Angular distributions of α_{0} and α_{1} have been measured for E_{p} up to 43.7 MeV. At the highest energy the angular distributions to the 0^{+} states ^{12}C*(0, 7.7, 17.8) are fitted by L = 1. The distributions to ^{12}C*(14.1, 16.1) [J^{π} = 4^{+}, 2^{+}] are consistent with L = 3; see (1980AJ01). For work on cross sections and resonances see ^{16}O in (1986AJ04) and (1988HO1F). See also (1987WE1C, 1988CA26; astrophysics) and (1984BE1A, 1984HA1Q, 1986LE1L, 1986RO18, 1988GN1A; applications).
At E_{α} = 42 MeV angular distributions involving ^{12}C*(0, 4.4) and ^{7}Li*(0, 0.48) have been obtained: see (1980AJ01). See also (1988SH1E; theor.).
For reaction (a) see (1986BA50; astrophysics) and (1984GL11, 1987BU1A; theor. [γ, 2d]). For reaction (b) see (1987HO1E). See also ^{16}O in (1986AJ04) and (1988BU06; theor.).
This reaction proceeds primarily to ^{12}C*(0, 4.4) at E_{p} = 101.5 MeV (1984CA09): ^{12}C(14.1) is also populated. The breakup into 4α has been studied by (1986VD04). See also (1985AJ01), (1987LA11, 1988LE08, 1988MU1G; astrophysics) and (1985VD03, 1987VD1A) and (1986GO28; theor.).
Angular distributions have been measured at E_{d} = 12.7 to 80 MeV [see (1980AJ01, 1985AJ01)], at 54.2 MeV (1984UM04; ^{12}C*(0, 4.4, 7.7, 9.6, 14.1)) [see also for spectroscopic factors] and at E_{pol. d} = 18 and 22 MeV (1987TA07; ^{12}C*(0, 4.4)) and 51.7 MeV (1986YA12; ^{12}C*(0, 4.4, 14.1)). For polarization measurements see ^{18}F in (1987AJ02).
Angular distributions have been studied at E(^{3}He) = 30, 41 and 70 MeV: see (1980AJ01, 1985AJ01). ^{12}C*(0, 4.4, 7.7, 9.6) are populated. See also (1986BA89; astrophysics) and (1987RA37; theor.).
At E_{α} = 90 MeV angular distributions involving ^{12}C*(0, 4.4) (reaction (a)) have been analyzed by PWIA and DWBA: S_{α} = 2.9 ± 0.5 and 0.70 ± 0.23, respectively. At E_{α} = 65 MeV angular distributions involving ^{8}Be_{g.s.} (reaction (b)) and ^{12}C*(0, 4.4, 7.7, 9.6, 14.1) have been measured [the ground state distributions have also been studied for E_{α} = 55 to 72.5 MeV]: S_{α} = 0.25, 1.07, 0.05, 1.40 for ^{12}C*(0, 4.4, 7.7, 14.1): see (1980AJ01) for references.
For reaction (a) see (1988WE17) and ^{13}C in (1991AJ01). For reaction (b) see (1986CA24) and ^{20}Ne in (1987AJ02). See also (1988AU03), (1984ME10, 1989VO1D) and (1984AP03, 1984KO13, 1987GA1L, 1988GA19, 1988GA1L; theor.).
Angular distributions have been obtained at E_{d} = 9 to 14.5 MeV: see (1980AJ01, 1985AJ01). ^{12}C*(0, 4.4) are populated.
Angular distributions have been measured in the range E_{α} = 13.4 to 20.8 MeV: see (1985AJ01). See also (1985ST1B) and (1988SH1F; theor.).
Angular distributions involving ^{12}C_{g.s.} have been studied at E_{p} = 7.9 to 18.6 MeV (1987KI26).
See (1986GO26; E_{d} = 13.6 MeV).
The fission of ^{24}Mg has been studied at E_{p} = 190 MeV (1987DA01).
Angular distributions have been reported at E_{α} = 22.8 to 25.4 MeV and at 90 MeV [see (1980AJ01)], at 25.13 to 27.76 MeV (1986SK01) and at 27.8 to 29.4 MeV (1989ES06). See also (1987SH1B) and (1988SH1F; theor.).
The fission of ^{24}Mg has been studied at E(^{24}Mg) = 357 MeV (1986WI14).
