(See the Energy Level Diagram for 10B)
Five resonances are observed in the range Eα = 0.5 to 2.6 MeV, corresponding to 10B*(4.76 - 6.06 MeV): see Table 10.5 (in PDF or PS). No other resonances appear for Eα < 3.8 MeV (10B*(6.74)) (1957ME27).
The 4.76-MeV state decays mainly to 10B*(0.7). The angular distribution of γ-rays indicates J = 2+, with a ratio E2/M1 = 1.8 (1957ME27), E2/M1 = 0.68; J = 3+ is possible, but unlikely (1957WA07). The strength of the E2 radiation is ≈ 0.01 eV, several times the single-particle value (1957ME27). The relative weakness of the M1 transition may reflect the predicted inhibition of such transitions for Tz = 0, ΔT = 0 transitions (1958MO17). The weakness of the ground-state radiation is puzzling (1953WI32). Observation of γ-decay in 9Be(d, n)10B suggests Γγ ≈ Γα (1958ME81).
The 5.11-MeV level was not observed by (1954JO09) who estimated ωΓs < 0.02 eV (Γs = ΓαΓγ/Γα + Γγ). According to (1957ME27), ωΓs = 0.1 eV. The angular distribution admits J = 2+ and 4- as possible assignments; J = 3+ is possible but unlikely. The earlier suggested assignment J = 2- appears to be excluded. On the other hand, (1958ME81) observe that the angular distribution can be accounted for by J = 2- if E1 radiation is strongly inhibited, i.e. if T = 0. See 9Be(d, n)10B and 9Be(p, γ)10B.
Angular distributions of gamma radiation from the 5.16-MeV level admit J = 1+ or 2+; 1- and 2- are possible, but unlikely (1957ME27). Observation of a γ-decay in 9Be(d, n)10B strongly supports the suggestion that Γα ≈ Γγ and that the reported width is largely experimental (1958ME81). In this case, the assignment T = 1 is indicated (1954JO09, 1959WA16). See also (1957KU58; theor.).
For the 5.92-MeV level, J = 2±, 3+ and 4+ are possible. Only J = 4+ gives a satisfactory account of the angular distribution from the 6.02-MeV level. The ratio E2/M1 = 9.0 (1957ME27).
Thresholds for production of slow neutrons are observed at Eα = 4.379 ± 0.006 MeV (10B(0)) and Eα = 5.51 MeV (10B*(0.71)) (1957BI84). Thresholds at Eα = 4.45, 5.64, 6.49 and 7.15 MeV are reported by (1956RO06): 10B*(0, 0.76, 1.30, 1.72). At Eα = 8.16 MeV, neutron groups corresponding to 10B*(0, 0.72, 1.32, 1.71) are reported. It is noted that the 1.3-MeV level is not observed in any other reaction (1956RO06). See also (1957NE1B).
Observed resonances are listed in Table 10.6 (in PDF or PS). An earlier reported resonance at 0.49 MeV is not confirmed (1955LO1A, 1956CL69). Cross sections from Ep = 30 to 250 keV are reported by (1953SA1A: see (1957JA37)).
The Ep = 0.33-MeV resonance (10B*(6.89)) has been the object of considerable study. The proton width indicates s-wave formation (1956WI16); the isotropy of the radiation is consistent with this assignment (1955CA25, 1956CL69). Of the possibilities J = 1- or 2-, the latter appears to be excluded by the strength of the transition to 10B*(1.74, J = 0+; T = 1) (1956WI16). The angular correlation in the cascade 10B*(6.89 → 0.7 → g.s.) is consistent with J = 1- (E1)1+(E2)3+ (1957BI75). The strong E1 transition to 10B*(1.74) and the large deuteron width indicate T = 0 for the 6.89-MeV level. On the other hand, the transitions to 10B*(0.7, 2.1) are nearly as strong, and would appear to require a T = 1 admixture of the order of 20%. Such a large admixture might be ascribed to a neighboring J = 1-; T = 1 state of the same parentage (9Be + s-wave proton) (see, however, (1957BA1J)). The strong M1 transition to 10B*(5.11) and the absence of the E1 transition to 10B*(5.16) present some difficulty (1956WI16). According to (1959ME1C) however, the observed transition is not to 10B*(5.11) but rather to 10B*(5.16); also this transition is not strongly resonant in this region. The 6.2, 5.2 and 4.7-MeV γ-rays all show the same resonance, excluding the possibility that two states may be involved. The ground-state transition shows only a monotonic rise, attributable partly to direct capture and partly to the tail of the 993-keV resonance (1958ED16). The angular correlation of 1.0 and 0.7-MeV γ-rays is consistent with J = 1+ or 2+ for 10B*(0.7) (1955CA25).
For Ep = 380 to 460 keV (thick target), a 2 - 4 % anisotropy is observed in the high energy radiation (Eγ > 3 MeV). At Ep = 600 keV, (thick target), the cascade 10B*(6.9 → 3.58 → 0.7 → g.s.) is observed, with an intensity of 0.35 that of the (6.9 → 1.74) cascade. It is suggested that the intensity of this transition implies a strong T = 1 admixture in 10B*(3.58) (1957BI75).
The broad resonance at 0.99 MeV (Ex = 7.48 MeV) is also believed to be formed by s-waves. The angular distribution of the γ-radiation suggests dominant s-wave formation with some d-wave contribution (1949DE1A, 1953PA22); see, however, (1956MO90). The resonance is located at 993 ± 2 (1953HO1C: Γ = 88 ± 3 keV), 989.5 ± 1.4 keV (1956HU1B: Γ = 91 ± 5 keV). Assuming J = 2, Γγ = 23 eV (1953HO1C). The strength of the transition to the ground state indicates E1, T = 1 (1953WI1B): again, as in the 6.89-MeV level, a considerable contamination is required, since 9Be(p, d)8Be and 9Be(p, α)6Li are also resonant. Study of the angular correlation of internal conversion pairs indicates about equal contributions of E1 and E3 or M2 transitions (1954DE1D). It is suggested by (1956MO90) that the observed transitions actually arise from two levels at 980 keV, (J = 2+) and 993 keV, with (J = 2-): see 9Be(p, p)9Be.
The narrow 7.56-MeV level [Ep = 1085 ± 2 keV (1953HO1C), 1083.7 ± 0.7 keV, Γ = 3.8 ± 0.5 keV (1956HU1B)] decays mainly to the 0.7-MeV state (1953HO1C: Γγ = 6.0 eV assuming J = 0). The angular distributions of these γ-rays and the subsequent 0.7-MeV γ-rays are isotropic, consistent with J = 0 (1953PA22). From Ep = 1.1 MeV to the neutron threshold at 2.06 MeV, no further structure is observed except a possible broad level tailing off from 1.15 to 1.55 MeV (1955KI1B): see 9Be(p, d)8Be and 9Be(p, p)9Be.
The excitation curve for Eγ > 6 MeV shows a pronounced resonance at Ep = 2.567 ± 0.003 MeV, and another, ≈ 0.5 MeV wide, superimposed on a general rise, at Ep = 4.72 ± 0.01 MeV. At the 2.6-MeV resonance, the capture radiation appears to proceed predominantly to the 0.7-MeV state (1953MA1A). It would appear from the width that this resonance corresponds to the 9Be(p, αγ)6Li resonance, J = 2+, and not to the 9Be(p, n)9B resonance, J = 3+, at the same energy (see (1956MA55)).
Resonances in the neutron yield occur at Ep = 2.56, 4.70 and (4.90) MeV (1952HA10, 1955MA84, 1956MA55, 1959GI47, 1959MA20); see (1957JA37) and Table 10.6 (in PDF or PS). A broad maximum (θ = 90°) near Ep = 3.5 MeV suggests an additional 10B state at 9.7 MeV with Γ ≈ 0.7 MeV (1956MA55, 1959MA20). Angular distributions are nearly isotropic near Ep = 2.56 MeV but show marked structure at higher energies (1956MA55). The excitation function for ground-state neutrons (n0) does not show the resonance at 4.9 MeV. If this peak represents neutrons leading to 9B*(2.3), it may arise from the tail of the Ep = 3.5-MeV resonance rather than from a new level. A continuous distribution of neutrons, observed for Ep > 4.5 MeV, is attributed to excitation of 9Be*(2.4) followed by breakup via 8Be*(2.9) (1959MA20).
The 2.56-MeV resonance is believed to be distinct from the resonance observed at the same energy in 9Be(p, αγ)6Li, because of its greater width (93 keV vs. 38 keV). Estimates of the reduced proton and neutron widths agree well with the known parameters of the 7.37 MeV, J = 3+; T = 1 state of 10Be. Assignment of J = 3+ to the 10B state accounts for the absence of 9Be (p, αγ)6Li γ-rays at this resonance (1956MA55). See also (1957ST1D, 1958MA1F, 1958TA03).
For Ep = 0.22 to 0.78 MeV, the elastic scattering is adequately described by s-wave formation of a broad level at Ep = 330 keV, J = 1- or 2-. For J = 1-, Γp/Γ = 0.30 (1956MO90).
In the range Ep = 0.8 to 1.6 MeV, attempts to fit the scattering data with s-waves are only moderately successful. That the major contribution at the 980-keV state is s-wave is indicated by the existence of interference minima at all angles near Ep = 1 MeV. Inclusion of d-waves, J = 2-, does not improve the fit. The best account of the behavior of the cross section in this region is obtained with the assumption of two s-wave resonances, J = 2-, at Eres = 998 and 1330 keV, Γp/Γ = 0.65 ± 0.15, Γ(998) = 150 ± 50 keV, Γ(1330) = 400 ± 100 keV, θ2p ≈ 0.006 and 0.15, respectively, superposed on a p-wave, J = 2+ resonance at 980 keV (see below). There is also some hint of a higher s-wave, J = 1-, resonance (1956MO90). (1956DE33) also finds that the Ep = 998 keV level is formed by s-waves, with Γ = 90 keV, Γp/Γ = 0.7. The scattering near 1.1 MeV requires a broad p-wave resonance at 1.1 MeV, Γ = 200 keV, Γp/Γ small (1956DE33).
At the 1084-keV resonance (10B*(7.56)), the smallness of the scattering anomaly indicates J = 0. Absence of interference at θ = 90° suggests l = 1, hence J = 0+. A satisfactory fit is obtained with the inclusion of a p-wave, 2+, state in the background. The 2+ state appears to be formed with channel spin 1, Γp/Γ ≈ 0.9 and to be located within a few hundred keV below 1084 keV. A fit to the data near 1 MeV gives Eres = 980 ± 10 keV, Γ = 90 keV, θ2p ≈ 0.07 (1956MO90). A scattering anomaly has also been observed at Ep ≈ 2.56 MeV. This anomaly increases in the backward direction indicating p-wave formation of a level at 8.89 MeV with J ≥ 2, Γp large (1956DE33).
Recent work on differential cross sections has been done in the range Ep = 5.4 to 31.5 MeV by (1952BR52, 1953WRZZ, 1956DA03, 1956KI54, 1956KL55, 1956RA32). See also (1955GR12, 1955HI1B, 1958BR24) and 9Be.
Excitation functions and angular distributions have been studied for Ep = 0.3 to 1.3 MeV by (1949TH05, 1951NE03, 1956MO90) and for Ep = 0.8 to 3.0 MeV by (1956WE37). Observed resonances are listed in Table 10.6 (in PDF or PS). Angular distributions at the 330-keV resonance are isotropic, consistent with s-wave formation (1956MO90). Proton and deuteron reduced widths for this resonance are evidently quite large, while the α-width is some 10 times smaller (1956MO90, 1956WI16). For Ep > 500 keV, the distributions show strong interference terms, implying contributions from states of both parities (1951NE03, 1956WE37). It is noted by (1956MO90) that the states appearing in 9Be(p, p)9Be are not sufficient to account for this interference, and an additional p-wave state near Ep ≈ 700 keV offers a plausible solution; see also (1958ME81). Above Ep = 1.8 MeV, pronounced pickup is evident in the (p, d) reaction (1956WE37).
A pronounced maximum occurs in the integrated cross section for both reactions at Ep = 930 keV, Γ = 130 ± 30 keV, presumably due to the J = 2-; T = 1 resonance seen in 9Be(p, γ)10B and 9Be(p, p)9Be at Ep = 991 keV. The reason for the energy shift is not clear. An appreciable T = 0 contamination is required; this may be due to the 1330-keV, J = 2-, resonance which appears in the (p, d), (p, α), (p, p) and possibly (p, γ) yields (1956WE37).
The 7.56-MeV state is not resonant for (p, α) or (p, d); this observation is consistent with its J = 0+ character. Broad, weak maxima occur in the total (p, d) cross section at Ep = 1.25, 1.64 and 2.3 MeV; the 90° (p, α) cross section shows maxima at Ep = 1.25, and ≈ 2.0 MeV with a small anomaly at Ep = 2.56 MeV, Γ = 40 ± 10 keV. The Ep = 1.25-MeV structure is probably associated with the Ep = 1.33-MeV resonance in 9Be(p, p)9Be, while the 2.56-MeV anomaly is clearly connected with the strong resonance at that energy seen in 9Be(p, αγ)6Li (J = 2+; T = 1). An upper limit to the deuteron width at this resonance is Γd = 13.5 keV, θ2 = 4.5 × 10-3. For α0 particles, 0.08 < Γα < 4.0 keV, 2.2 × 10-5 < θ2α < 1.1 × 10-3 (1956WE37). For the (p, α2γ) reaction, the resonance occurs at 2.562 ± 0.006 MeV, Γ = 38 ± 3 keV, θ2n + θ2p = 0.0032 (1954MA1C, 1956MA55: Γ = 41 ± 2 keV). From the fact that this state (10B*(8.89)) decays primarily to the J = 0+; T = 1 state of 6Li (3.58 MeV) it is concluded that it has T = 1 (1954MA1C, 1954MA26). The observed cross section requires J ≥ 2, while the width requires J ≤ 2. For J = 2, θ2α2 = 0.19 or 0.33, θ2n = 0.0016 (1954MA26). This resonance is presumed to be distinct from the 9Be(p, n)9B resonance which occurs at the same energy (1956MA55). A further resonance for 6Li*(3.6) γ-rays appears at Ep = 4.49 MeV, and a broad rise near Ep = 3.5 MeV, observed in 9Be(p, n)9B, seem also to be found here. It is suggested that these states have T = 1 and correspond to 10Be*(9.27) and 10Be*(9.4) (1959MA20).
Neutron groups are observed corresponding to 10B states listed in Table 10.7 (in PDF or PS): see (1951AJ1A, 1952PR1A, 1953PR1A, 1955GE1B, 1955GR1D, 1957MU1D, 1957NE1C, 1957SH65, 1958GE04, 1958NE38). Thresholds for slow neutron production corresponding to 10B states from 4.77 to 6.57 MeV are reported by (1954BO79). Indications of a state at 2.8 MeV are reported by (1953DY1A, 1954RE1A, 1958GE04). Angular distributions to the low states have been studied at many energies from Ed = 0.5 to 3.4 MeV: see (1952AJ22, 1952PR1A, 1953PR1A, 1955GE1B, 1955GR1D, 1957NE1C, 1957SH65). The data show evidence both for stripping and compound nucleus formation with more evidence of the former in the higher energy work: the ground state and the first four excited states have J ≤ 3 and even parity, and one or both of the 5.1-MeV levels have J = 1- or 2- (1952AJ22). It is of interest that the 3.6-MeV state shows a well developed stripping pattern even at the lowest bombarding energies. According to (1958SA17, 1959NE1A), however, the character changes drastically at Ed = 1.5 to 2 MeV, suggesting some contribution of "heavy particle" stripping. The group leading to the 0.72-MeV state also shows this effect. See also (1956MA1N; theor.). Absolute reduced widths for several levels have been estimated by (1958ME81) using published cross section data: see Table 10.7 (in PDF or PS).
The mean lifetime of the 0.72-MeV state is (7 ± 2) × 10-10 sec (1953TH14), (8.5 ± 2.0) × 10-10 sec (1956SE08), (11.8 ± 3.3) × 10-10 sec (1958GO47, 1958KN1B), (9.6 ± 1.0) × 10-10 sec (1958DA11); compare with 10B(p, p')10B*. The γ-ray energy is 716.6 ± 1 keV (1949RA02). The 1.74-MeV state (J = 0+; T = 1) decays via the 0.7-MeV state: Eγ = 1022 ± 2 keV (1949RA02). The ground-state transition is < 10% (1951AL1B). See also (1954SH1A).
The 2.1-MeV state decays directly to the ground state and via cascades through the 0.72 and 1.74-MeV levels; Eγ = 2151 ± 16, 1433 ± 5, 413.5 ± 1 keV; the intensities are in ratio 1.2 : 2.5 : 1.2 (1949RA02). The relative contribution of the 1400-keV γ-ray is uncertain since this radiation also arises from the transition 3.58 → 2.1 (1954SH1A). The relative strength of the low energy, 2.1 → 1.7 MeV, transition is attributed to a strong inhibition of the M1, ΔT = 0 transition from 10B*(2.1 to 0.7) (1958MO17: see also (1957KU58)). For the 3.58-MeV level. the ground state transition is about 1/3 as intense as that to the 0.7-MeV state (1949RA1B: see also (1957MC35, 1958CH1A)). The transition (3.58 → 2.1) also occurs (1954SH1A). The angular correlation (2.86 → 0.7) is consistent with J = 1+ or 2+ for the 3.6-MeV level; J = 0, 3 are excluded. For J = 2+, acceptable schemes are 2 (0.93 M1 + 0.07 E2)1(E2)3 or 2(E2)1(E2)3 (1956SH94). A spin 1+ assignment would permit a strong M1 transition to the J = 0+; T = 0 state at 1.74 MeV (1958MO17).
The fact that gamma radiation is observed in competition with α-decay from the 4.77 and 5.16-MeV levels suggests that Γγ ≈ Γα for these two states. No radiation is observed from the 5.11, 5.93, or 6.06-MeV levels in 9Be(d, n)10B (1958ME81: see also (1959NE1A)). No gamma rays of energy 6.5 to 8.0 MeV are observed with intensity > 5% of the 6.0-MeV, 10Be radiation (1955BE81: Ed = 3.85 MeV). The ratio of 5.16 → g.s. to 5.16 → 0.7 radiation is 1 : 2 (1955BE81: see, however, (1957MC35)).
At Ed = 9 MeV, the ratio of the maximum differential cross sections of the 9Be(d, p)10Be and 9Be(d, n)10B reactions to the first T = 1 states leads to a ratio of reduced widths of 2.16 (calculated from stripping theory; predicted value from charge independence: 2) (1956CA1D). See also (1956BA1F, 1956BO1F, 1956BO43, 1956DE1D, 1956GO1H, 1957GR1A, 1958BE03).
At E(3He) = 2.1 MeV, gamma-rays from the 0.72-MeV state have been observed (1957FE1B). At E(3He) = 5.7 MeV, deuteron groups are observed to the ground state of 10B and to levels at 0.724 ± 0.010, 1.751 ± 0.010, and 2.163 ± 0.010 MeV (S. Hinds and R. Middleton, private communication). The angular distributions follow quite closely the lp = 1 stripping patterns.
In the range Eγ = 10 to 30 MeV, reaction (a) proceeds almost entirely through excited states of 8Be: transitions via (α + d)-emitting states of 6Li apparently do not occur. Reaction (b) is said to proceed via the ground state and γ-emitting states of 6Li at 1.1 and 2.2 MeV (1953ER1A) (there is no evidence for a state at 1.1 MeV in any other reaction: see (1952AJ38) and (1955AJ61)). For reaction (d) see (1956GO1F, 1956GO1G, 1957BA1H).
At En = 2.56 MeV, a 717 ± 7 keV γ-ray is observed (1956DA23).
The first seven excited states have been accurately located by inelastic scattering: see Table 10.7 (in PDF or PS) (1953BO70, 1953BR1A). The energy of the first state is given as 717 ± 5 keV (1953BO70), 719 ± 1.6 keV (1952CR30) and 718 ± 5 keV (1954DA20: γ-radiation). The mean life of this state is (10.5 ± 1.0) × 10-10 sec (1957BL02), (9.0 ± 1) × 10-10 sec (1958HO97). This lifetime is about a factor of 10 shorted than that calculated on the shell model with reasonable values of the radius and intermediate coupling parameter (1957BL02: see, however, (1957FR1B, 1957KU58); see also 9Be(d, n)10B).
At Ep > 3 MeV, gamma rays of energy 710 ± 15, 1023 ± 5, 1438 ± 5, and 2120 ± 60 keV are observed (1957HU79, 1957MC35). An upper limit of 7% is found for direct transitions from 10B*(1.74 → g.s.) (1957MC35). At Ep > 4.5 MeV, additional radiations at 2860 ± 10 and 3560 ± 50 keV (Doppler corrected) are observed, with intensity ratio 2.9. Shell model calculations would predict a ratio of 0.67 to 0.5 (1957MC35: see also (1957KU58)).
Deuteron groups corresponding to the ground state and to states at 0.7, 2.1, and 3.6 MeV are reported by (1953BO70): see Table 10.7 (in PDF or PS). The absence of deuteron groups corresponding to the 1.74-MeV state is strong evidence of its T = 1 character.
The half-life is 19.1 ± 0.8 sec (1949SH25); Eβ+(max) = 2.2 ± 0.1 MeV. The β+-decay is to the first two excited states of 10B: relative transition probabilities to the 0.72-, 1.74- and 2.15-MeV levels are 98.4/1.65 ± 2/< 0.1 (1953SH38): log ft using Eβ(max) = 2.04 and 1.02 MeV (from Qm above) are 3.2 and 3.7. The gamma decay of the first two excited states of 10B is observed: Eγ = 723 ± 15 and 1033 ± 30 keV (1953SH38). See also (1953KO1B), (1957FR1B) and (1958GE33).
At Ep = 18.9 MeV, the ground state deuteron angular distributions indicate ln = 1 (1956RE04).
These reactions have not been reported.
At Ed = 8.9 MeV, α-groups have been observed corresponding to the ground state of 10B and to excited states at 0.72 ± 0.02 and 2.14 ± 0.02 MeV. No α-group was observed to the T = 1, 1.74-MeV state (1957EL12). See also (1951AS1A) and (1953SP1A).
Arguments supporting the Jπ assignments for the first five excited states of 10B are presented in reaction 20 in 10B in (1955AJ61). The assignment of the 4.77-MeV state now appears to be J = 2+ (see 6Li(α, γ)10B).