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15O (91AJ01)(See Energy Level Diagrams for 15O) GENERAL: See also (86AJ01) and Table 15.16 [Table of Energy Levels] (in PDF or PS) here. Nuclear models:(87ST05). Special states:(85SH24, 86LI1B, 87ST05, 88AN1E, 89WU1C). Electromagnetic transitions:(84VA06, 87HO1L, 87ST05). Astrophysical questions:(85TA1A, 87RA1D, 89JI1A, 89ST14, 90RA1O). Complex reactions involving 15O:(85FI08, 85HU1C, 85PO11, 85SI19, 86GR1A, 86ME06, 86PO06, 86TO10, 86UT01, 87BA38, 87BE1I, 87BU07, 87NA01, 87RI03, 87ST01, 88BE02, 88BE56, 88MI28, 89BA92, 89CA25, 89DR03, 89KI13, 89PO07, 89SA10, 89TA1O, 89YO02). Applied work:(85BO1P, 85HA40, 87HI1B, 88HI1F, 88VO1D, 89AR1J, 89WO1B). Pion and other mesons capture and reactions (See also reactions 8, 16, 17 and 21.): (86LI1B, 87LE1B, 88CH1H, 88MI1K, 89LE1L, 90OD1A). Hypernuclei:(84ZH1B, 86DA1G, 89BA93, 89KO1H, 89TA17). Other topics:(85AN28, 85SH24, 86AN07, 86WI03, 87CH02, 89WU1C, 90MU10). Ground-state properties of 15O:(85AN28, 85AR11, 86MC13, 86WI03, 86WUZX, 87FU06, 87SA15, 88AR1B, 88CH1T, 88FU04, 88NI05, 88SH07, 88VA03, 88WA08, 89CH24, 89FU05, 89NE02, 89SA10).
15O*(5.24): μ = +(0.65 ± 0.07) nm: see (89RA17).
The half-life of 15O is 122.24 ± 0.16 s: see (81AJ01); log f0t = 3.637. The K/β+ ratio is (10.7 ± 0.6) x 10-4: see (76AJ04). The β-anisotropy has been measured by (88SE11, 89DE07). See also (86AJ01), (90ST08), (85BA1N, 85BA1M, 86GR04, 87BA1U, 87FR1C, 87RI1E, 87WE1C, 88BA1H, 88BA1Y, 89BA2P, 89DA1H; astrophysics) and (88TA09, 88TO1C, 89WO1E; theor.).
For reaction (a) see (86BE54); for reaction (b) see (86BE35). For other heavy-ion reactions see (86AJ01).
Excitation functions and polarization measurements for these reactions have been measured over a wide range of energies: see Tables 15.20 in (70AJ04 (in PDF or PS), 76AJ04 (in PDF or PS), 81AJ01 (in PDF or PS)) and the text below. Observed resonances are displayed in Table 15.18 (in PDF or PS) here.
The 90° yield and the angular distributions of γ0, measured from E(3He) = 5.24
to 13.95 MeV show five resonances attributed to E1 transitions from Jπ = 1/2+ or 3/2+, T = 1/2 states
in the GDR characterized by a considerable 3p4h admixture ((78DE33) [also for
ωγ], (84DE09)). Yields of
γ1+2 at 90° have also been reported at
E(3He) = 5.3 to 16.7 MeV: the cross section is some eight times
greater than that for (3He, γ0)
and is similar to that for the
The yield of n0 (reaction (b)) shows resonances for
E(3He) < 10 MeV and little structure above, to 30.6 MeV: see (81AJ01) [n1 and
n2+3+4 yields are also reported].
The yield of protons (reaction (c)) shows some clear resonances below
E(3He) = 4.5 MeV and some uncorrelated structures at higher
energies (to E(3He) = 12 MeV) with the possible exception of
states at Eres = 7.8, 9.2 - 9.6 and (10.5) MeV. For
E(3He) = 16 to 30.6 MeV no appreciable structure is observed in
the p0, p1 and p2 yields: see (76AJ04). At
E(3pol. He) = 33 MeV Ay has been measured for
14N*(0, 2.31, 3.95): see (86AJ01). For polarization effects
in the (3He, 2p) reaction at E(3pol. He) = 33 MeV see
(86KA44). For
reactions (d) and (e) see (76AJ04, 81AJ01, 86AJ01).
The elastic scattering (reaction (f)) shows some resonant structure near 3, 5 and 6
MeV and some largely uncorrelated structures in the range E(3He)
= 16.5 to 24 MeV. There is some suggestion, however, of two resonances at
E(3He) = 17 and 20 MeV: see (76AJ04). Resonance-like behavior is
also reported at E(3pol. He) = 29 MeV. Polarization measurements
are reported for E(3pol. He) = 20.5 to 32.6 MeV: see (81AJ01). See also (86AJ01). The yield of α-particles displays resonance structure below 8 MeV, and
broad fluctuations for E(3He) = 12 to 18.6 MeV: see (76AJ04). Polarization measurements
are reported for E(3pol. He) = 33.3 MeV for the α0 and α1
groups: see (81AJ01). For
Ay measurements of the (3He, 7Be) and
(3He, 6Li) reactions see (89SI02, 86CL1B). For π± production see (86MI25). For a
search for subthreshold K+ production see (85IA01). For work
at very high energies see (85AB1B, 85AD1C). See also (86AJ01), (84NA1F), (90TO10; applied)
and (86EV01, 86SI02; theor.).
Angular distributions of the n0 group have been measured for Eα = 18.4 to 23.1 MeV: see (76AJ04). At Eα = 41 MeV angular distributions are reported to
15O*(5.24, 6.86 + 7.28, 9.63[u], 10.48[u], 11.72[u], 12.85[u],
15.05[u]). 15O*(8.92, 11.1, 12.3, 13.45, 13.72, 14.27, 15.65) are also
populated ((81OV1B)
[uncertainties in Ex are not shown; unresolved states are a problem]).
At Eα = 47.4 MeV groups are populated at
θ = 0° corresponding to
15Og.s. and to unresolved states at 5.2, 7.3, 10.0, 12.5 and
15.3 MeV (88LU02). See also
(88CA26;
astrophys.).
States observed in this reaction are displayed in Table 15.19 (in PDF or PS) (75BI06:
E(6Li) = 59.8 MeV). Comparisons of angular distributions of the
triton groups in this reaction and of the 3He groups to analog states in
15N have been made: analog correspondence is established for (10.48 -
10.70), (12.84 - 13.15 (u)) and (15.05 - 15.49 (u)) [Ex in
15O, Ex in 15N; u = unresolved] (75BI06). See also
(76AJ04) for the earlier work.
At E(12C) = 187 MeV, θlab =
8°, the spectrum is dominated by 15O*(12.84, 15.05) [assumed
Jπ = 1/2-, 13/2+,
respectively]. 15O*(7.28) [Jπ =
7/2+] is populated but 15O*(0, 6.79) are not observed. The
situation is similar at E(12C) = 114 MeV but at
E(12C) = 72 MeV (θlab =
11°) 15O*(0, 5.2, 7.28) are populated with comparable intensities:
see (76AJ04).
At E(12C) = 480 MeV the three most strongly excited states in the
forward direction are 15O*(10.46, 12.83[u], 15.05[u]) [Jπ = 9/2+, 11/2-, 13/2+]
and forward angle σ(θ) have
been measured. 15O*(0, 5.24, 7.3, 8.9[u], 16.7[u], 18.2[u], 21.1[u],
22.1[u]) are also populated (88KR11).
Observed groups are displayed in Table 15.22 (in PDF or PS) of (81AJ01).
At Epol. p = 183 MeV differential cross sections and Ay are
reported for the transitions to 15O*(0, 7.3), the two states strongly
populated in the reaction (82JA05, 82VI05). See also
(86JA1H) and (86KU1J, 90KU1H; theor.).
Observed resonances in the yield of γ-rays are listed in
Table 15.20 (in PDF or PS). Branching ratios are displayed in
Table 15.17 (in PDF or PS). Measurements of Eγ lead to Ex = 5183 ± 1, 5240.9 ±
0.4, 6175 ± 2, 6794 ± 2, 6858 ± 2, 8284.1 ± 0.8, 8922 ± 2
and 8978 ± 2 keV: see (81AJ01)). For τm see (81AJ01).
(87SC1H) have studied
absolute cross sections, γ-ray angular distributions and
excitation functions for Ep = 0.2 to 3.6 MeV: S(0) is determined to be
3.20 ± 0.54 keV · b. C2S are derived for the first eight
states of 15O (87SC1H).
The 90° γ0 yield has been measured for
Ep = 2.2 to 19 MeV: resonances are observed over most of the range. The
(γ1 + γ2) yield is relatively weak. For Ep =
18 to 28 MeV the excitation function for γ0
decreases smoothly with energy: there is no evidence for structures [see (81AJ01)]. See also (85CA41, 87KR04, 87WE1C, 88CA1J, 88CA26, 89BA2P, 89TH1C, 90MA1P; astrophysics) and (90HA46; theor.).
The excitation function has been measured for Ep = 6.3 to 12 MeV: see
(70AJ04). Observed resonances
are displayed in Table 15.20 (in PDF or PS). The cross section [obtained by
measuring the 2.31 MeV γ-rays from the 14O
(β+) decay] is reported at 12 energies in the
range Ep = 7 to 22 MeV (81DY03). Production
cross sections for the 2.31 MeV γ-rays have been
measured at Ep = 8.9, 20, 30, 33 and 40 MeV by (88LE08). The ratio
of the cross section to 14Og.s. to that for the analog state
14N*(2.31) [from the (p, p') reaction] has been determined at
Ep = 35 MeV (84TA02).
Forward-angle differential cross sections (n0) are reported by (79MO16) at
Ep = 144 MeV. See also (85CA41; astrophys.)
and 14O.
The yields of elastic and inelastic protons, and of 2.31 MeV γ-rays, have been studied at many energies: see (59AJ76, 70AJ04, 76AJ04). Observed resonances are
displayed in Table 15.20 (in PDF
or PS). At higher energies
excitation functions have been measured for the p0, p1 and
p2 groups for Ep = 17 to 26.5 MeV: there is no evidence for
resonant behavior but the p1 yield shows a large increase between
Ep = 20 and 23 MeV. Total cross sections for the p0 --->
p9 groups have been measured at Ep = 8.6, 10.6, 12.6 and 14.6
MeV [see (81AJ01)]. Total
reaction cross sections have also been measured in the range Ep = 22.9
to 49.0 MeV by (85CA36). (88LE08) report
2.31-MeV γ-ray production cross sections at
Ep = 8.9, 20, 30, 33 and 40 MeV. For measurements at
E(14N) = 516 MeV/A see (90WE14).
Polarization measurements have been carried out at Ep = 3.0 to 159.4 MeV
[see (70AJ04, 76AJ04, 86AJ01)] and at Epol. p
= 35 MeV (90IE01;
p1) and 0.8 GeV (85BL22;
Ay; elastic). See also 14N, (86BA2U), (86BA88, 87HU01) and (89AM01; theor.).
Excitation functions for the ground-state group have been measured at Ep
= 7 to 11 MeV: some resonant structure is indicated [see Table 15.20 (in PDF or PS)]. See also (76AJ04).
Excitation functions and total cross-section measurements have been measured for
the α0 group for Ep = 3.8 to 45
MeV: see (76AJ04). Fairly sharp
structures persist until Ep = 15 MeV: see Table 15.20 (in PDF or PS) here and footnote e in
Table 15.23 (in PDF or PS) of (81AJ01). See also (86AI04; applied)
and (85CA41;
astrophys.).
Angular distributions have been studied at many energies in the range Ed
= 0.9 to 11.8 MeV: see Tables 15.27 (in PDF or PS) and 15.28 (in PDF or PS) in (70AJ04) and Table 15.26 (in PDF or PS) in (76AJ04). For τm measurements see (70AJ04). See also Table 15.21 (in
PDF or PS) here, 16O in (86AJ04), (87HI1B; applied) and (84BL21; theor.).
See Table 15.28 (in PDF or PS) in (70AJ04). See also Table 15.21 (in PDF or PS) here.
At Eγ = 170 MeV four-point angular
distributions of the π- to
15Og.s. have been measured by (88LI23) and (89KO28): the two
studies are not in good agreement. See also (90ER03; theor.).
Angular distributions of the π0 to
15Og.s. have been studied at Eπ+ = 32.4 and 55.5 MeV (85IR02), at 48 MeV
(84CO04, 86LE01) and at 165
MeV (82DO10).
Forward-angle differential cross sections of the π0 to 15Og.s. have also been
measured at Eπ+ = 20 MeV (87IR01) and at 40.7
and 63.6 MeV (85IR02). See also
(89LE1L).
Angular distributions have been measured for Ep = 3.95 to 18.5 MeV [see
(81AJ01, 86AJ01)], at 35 MeV (87OR01;
15O*(7.56) [Jπ =
1/2+]), at 135 MeV (85WA24;
15O*(0, 6.2)) and at 200 and 494 MeV (88CIZZ; prelim.;
also Ay). Forward-angle differential cross sections at Ep =
200, 300 and 400 MeV to 15O*(0, 6.2) are reported by (87ALZW; prelim.).
The ratio of the population of 15Og.s. to that of
15O*(6.2) has been determined at Ep = 800 MeV (86KI12).
15O*(6.2) contains only about 1/3 of the expected GT strength (85GO02). [I am
indebted to Prof. C.D. Goodman for his comments.] For a discussion of GT strengths,
see (87TA13).
15O*(5.2[u], 6.8[u], 7.28) have also been populated (87OR01). For the
earlier work see (86AJ01). See
also 16O in
(86AJ04), (85GO1Q, 86VO1G, 87BE25, 88RO17, 88WA1Q), (86MA1P, 87HI1B, 88HI1F; applied) and (89RA15; theor.).
Angular distributions for the t0, t1+2, t3,
t4+5, t6 and t7 groups have been studied for
E(3He) = 16.5 to 44.6 MeV: see (76AJ04).
The spectrum of photoneutrons has been investigated at many energies. Measurements
over the giant dipole resonance region show the predominant strength is to the
Jπ = 1/2- and 3/2-
states Ex = 0 and 6.18 MeV, consistent with the basic validity of the
single-particle, single-hole theory of photoexcitation in 16O. However,
the positive-parity states at Ex = 5.18, 5.24, 6.86 MeV are also
populated suggesting some more complicated excitations in 16O: (70AJ04, 76AJ04). Differential cross
sections for the n0 group have been measured from threshold to
Eγ = 28 MeV [see (76AJ04)], at Eγ = 60 to 160 MeV (also 15O*(6.18); no
appreciable strength in the 5.2 MeV doublet) [see (86AJ01)] and at 150, 200 and 250
MeV (89BE14).
See also 16O in
(86AJ04) and (87RY03, 88CA10, 88DUZX, 88RY03, 90BRZY, 90FL1A; theor.).
For reaction (a) see (82DO01). At
Eπ+ = 2.0 GeV/c
differential cross sections have been determined for the transition to
15N*(6.2) (83KI01) in reaction
(b). For reaction (c), see (86GI1A).
At Ep = 505 MeV the summed spectra show two peaks corresponding to the
p1/2 and p3/2 knockouts [15O*(0, 6.18)] (binding
energies of 15.64 and 21.82 MeV). Differential cross sections are also reported (86MC10) [see also
reaction 59 in
15N]. For work at 1 GeV, see (85BE30). See also
(83WA1C) and (87HI1B; applied).
Angular distributions have been reported at many energies for Ep = 18.5
to 155.6 MeV [see Table 15.30 in (70AJ04 (in PDF or PS)), (76AJ04), (86AJ01)]: at those energies
15O*(0, 6.18) are preferentially populated. At Ep = 200 MeV
angular distributions have been studied for 15O*(0, 6.18) (89AB01) [also
Ay and C2S]. At Ep = 800 MeV 15O*(0,
5.2[u], 6.18, 7.4[u], 9.0[u], 10.42 ± 0.15, 10.87 ± 0.15, 12.21 ±
0.15, 13.59 ± 0.15, 19.0 ± 0.2, 21.1 ± 0.2) [the last two states
have Γ >/= 0.8 MeV] have been populated (84SM04).
For γ-ray production [15O*(5.24)] see (88LE08). See also
17F in (86AJ04),
(89WA16) and (87LA11, 88LE08, 89GU28;
astrophysics).
Angular distributions have been reported at a number of energies in the range
Ed = 20 to 52 MeV [see (81AJ01) and reaction 60 in 15N
here] and at Epol. d = 89 MeV (90SA27;
15O*(0, 6.18)). See also 18F in (83AJ01).
The p1/2 and p3/2 hole states 15O*(0, 6.18) are
strongly populated. Information on these and other states are displayed in Table
15.25 (in PDF or PS) of (81AJ01). Angular distributions have
been measured at energies up to E(3He) = 217 MeV: see (81AJ01). Branching ratios and
multipole mixing ratios are displayed in Table 15.17 (in PDF or PS). (78BE1E) report τm of 15O*(5.24) = 3.25 ± 0.30 ps,
|g| = 0.260 ± 0.028. (83BI10) determine g
= +0.17 ± 0.07. See also (86AJ01), 19Ne in (83AJ01) and
(90AB1G; applied).
See (86GL1E; prelim.).
At Ep = 39.8 MeV angular distributions of t0 and
t3 groups have been compared to those of the 3He groups to
the analog states in 15N. At Ep = 45 MeV a state, assumed to
be the Jπ = 5/2+, T = 3/2 analog
of 15C*(0.74), is observed at Ex = 12.255 ± 0.013 MeV,
Γc.m. = 135 ± 15 keV. The state decays
by proton emission to the T = 1, 0+ state 14N*(2.31) [the
population of some T = 1/2 states is also reported]: see (81AJ01).
Epol. p = 89.7 MeV angular distributions and Ay measurements
have been reported to 15O*(0, 5.24[u], 6.18, 6.86, 7.28) (85VO12).
See (76AJ04). See also (86HA1E; theor.).
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