TUNL Nuclear Data
Evaluation Home Page

Information on mass
chains and nuclides
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
 
Group Info
Publications
HTML
General Tables
Level Diagrams
Tables of EL's
NSR Key# Retrieval
ENSDF
Excitation Functions
Thermal N Capt.
G.S. Decays
Half-Lives Table
TUNL Dissertations
NuDat at BNL
Useful Links
Citation Examples
 
Home
Sitemap
Directory
Email Us


WWW TUNL

USNDP

7Be (1979AJ01)


(See Energy Level Diagrams for 7Be)

GENERAL: See also (1974AJ01) and Table 7.6 [Table of Energy Levels] (in PDF or PS).

Nuclear models: (1974KA11).

Astrophysical question: (1973BA1H, 1973IB1A, 1973SM1A, 1973TR1C, 1973WE1D, 1974KO1C, 1974PA10, 1974RA09, 1974SH1D, 1975HO1C, 1975KI14, 1975SC1H, 1976BE1C, 1976BO1E, 1976CL1A, 1976CO1B, 1976FU1B, 1976GI1C, 1976HE15, 1976PE1A, 1976RA1C, 1976SI1C, 1976VI1A, 1977AU1B, 1977BA1V, 1977BI1E, 1977GA1C, 1977HA1L, 1977KO1J, 1977MO1E, 1977SC1D, 1977SI1D, 1978ME1D).

Electromagnetic transitions: (1974KU06, 1974MU1B, 1976KU07).

Special levels: (1974IR04, 1974KA11, 1976IR1B).

Applied work: (1976WI1B).

Special reactions: (1974BA70, 1974BO08, 1974DI16, 1974HA11, 1974KA22, 1974PA10, 1974PE1C, 1974RA09, 1974RA11, 1975FU01, 1975HO12, 1975HU10, 1975RA12, 1975RA14, 1975RA21, 1975RA25, 1975RE18, 1975RU09, 1975WI1D, 1975ZE01, 1975ZE03, 1976BE1K, 1976BO08, 1976BU16, 1976CU05, 1976DI01, 1976HE15, 1976HU1D, 1976IN04, 1976LE1F, 1976MA1D, 1976MI13, 1976OS04, 1976RA1C, 1976SI1D, 1976ST11, 1977AR06, 1977AS03, 1977BI1E, 1977GO07, 1977ST34, 1977ST1G, 1977YA1B, 1978BI08, 1978CU01, 1978DI04, 1978GE1C, 1978GR1F, 1978WE1D).

Reactions involving pions and kaons: (1975GI1B, 1976EN02, 1977AL21 : [Cross section for 7Li(π+, π0)7Be to 7Be*(0, 0.43) for Eπ = 90 to 210 MeV (1977AL21).], 1977SP1B, 1977WA02, 1978WA02).

Other topics: (1974DA1B, 1974IR04, 1975PN1A, 1976IR1B).

Ground state properties of 7Be: (1975BE31).

Spectroscopic factors (1975HU10)
p3/2 p1/2
7Beg.s. 0.37 0.35
7Be*(0.43) 0.95 0.00
1. 7Be(ε)7Li Qm = 0.862

The decay is complex: see 7Li.

2. 4He(3He, γ)7Be Qm = 1.586

In the range Eα = 0.38 to 5.80 MeV the cross section rises from 8 × 10-3 to 4 μb (1963PA12, 1969NA24). The capture proceeds mainly by E1, with both s- and d-waves contributing above Eα = 1 MeV (1963TO06). The branching ratio γ10 [7Be*(0.43)/7Be(0)] is approximately constant at 37% for Eα = 0.57 to 3.2 MeV (1963PA12, 1969NA24). The zero-energy intercept of the cross-section factor S = 0.61 ± 0.07 keV · b and (dS/dE)0 = -(5.8 ± 0.3) × 10-4 b using all the data. If the low-energy data (Ec.m. ≤ 0.7 MeV) is fitted using a direct capture calculation (1963TO06) the zero-energy intercept of the cross-section factor is S = 0.51 ± 0.05 keV · b and (dS/dE)0 = -(2.8 ± 0.4) × 10-4 b (1969NA24). A second-order (in energy) polynomial fit to the low-energy data (Ec.m. ≤ 0.8 MeV) determines S = 0.61 ± 0.07 keV · b and (dS/dE)0 = -(5.8 ± 0.3) × 10-4 b (1969NA24). Recent papers discussing the astrophysical implications of this reaction are (1971BA1A, 1974VA1C, 1976NO1C).

3. (a) 4He(3He, 3He)4He Eb = 1.586
(b) 4He(3He, p)6Li

Elastic scattering studies have been reported for E(3He) = 1.72 to 140 MeV [see (1974AJ01)] and at Eα = 22.8 to 26.4 MeV (1976ZA11) and 65.3 to 102.7 MeV (1973FE1B). The total reaction cross section at E(3He) = 28 MeV is 433 ± 10 mb (1977KO09). Polarization measurements have been carried out at E(3He) = 7.8 to 13 MeV and Eα = 4.3 to 18.5 MeV [see (1974AJ01)], E(3He) = 18 → 32 MeV (1978LU05), and at Eα = 24.5 to 42 MeV (1976BA1L; on 3He-bar), E(3He-bar) = 38.2 MeV (1976BI1C) and at Eα = 98 MeV (1973FE1B). For an R-matrix analysis of the 2F5/2 state at Ex = 6.73 MeV, see (1976DO1B).

For l ≤ 4, only f-wave phase shifts show resonance structure for E(3He) < 18 MeV, corresponding to 7Be*(4.57, 6.73, 9.27): see Table 7.7 (in PDF or PS) (1967SP10). No structure corresponding to 7Be*(7.21) (Jπ = 5/2-) is seen in the elastic data. The s-wave phase shift is somewhat greater than hard-sphere; the p-wave splitting agrees with (1964BA09, 1967SP10). The decay of 7Be*(9.27) (Jπ = 7/2-) to 6Li(0) requires f-shell configuration admixture. An estimate of the yield of ground state protons relative to those corresponding to 6Li*(2.19) yields γ2(p0)/γ2(p1) = (16+5-10)% (1967SP10). A phase shift analysis (single-level R-matrix) has been carried out for E(3He) = 18 to 32 MeV: the p-wave phase shifts indicate a 1/2- state at Ex ≈ 16.7 MeV (Er = 26.4 MeV), with Γ = 6.5 MeV (1978LU05). At higher energies [E(3He) = 27.2 to 42.8 MeV] (1969SC16) report that the s- and f-wave phase shifts fall appreciably below the predictions of resonating group calculations, while (1970BR42) see some indication of broad resonant structure at E(3He) ≈ 34 MeV, in rough qualitative agreement with such calculations. The bremsstrahlung cross section at E(3He) = 7.4 MeV is 12.6 ± 3.4 μb/sr2 (1973FR17).

The differential reaction cross section for reaction (b) has been determined for E(3He) = 8 to 18 MeV (1967SP10) and at 28 MeV (1977KO09: d0, d1, d2): resonances are observed corresponding to 7Be*(7.21, 9.27) in the p0 yield and to 7Be*(9.27) in the p1 yield: see Table 7.7 (in PDF or PS) (1967SP10). A study of the γ-rays from 6Li*(3.56) (p2) carried out at E(3He) = 13.8 to 18.5 MeV shows the excitation of two Jπ = 3/2- states at Ex ≈ 10.0 MeV (T = 1/2) and 11.00 ± 0.05 MeV (Γ = 400 ± 50 keV, θ2p2 = 0.13 ± 0.02, T = 3/2). The T = 3/2 resonance is evidenced mainly through interference. There is also some evidence for an extremely broad Jπ = 1/2- structure at Ex ≳ 10 MeV (1967HA07, 1967HA08: see also 6Li(p, p)6Li). At E(3He) = 28 MeV sequential breakup via 6Li*(2.19) significantly contributes to the reaction mechanism (1977KO09).

See also (1975TO1A, 1978BR1E) and (1974BA40, 1974KO03, 1974TE05, 1975BA05, 1975CL1C, 1975KU09, 1975TA1A, 1977BA1N, 1977BU01, 1977SA1C, 1978LE13; theor.).

4. 4He(α, n)7Be Qm = -18.992

The production cross section for 7Be has been measured for Eα = 39.4 to 47.4 MeV: it is essentially equal to that for the (α, p) reaction above 43 MeV but is smaller below because of threshold effects. See also (1977RA1B; prelim., Eα = 400, 600 and 1000 MeV). For a discussion of the production of 7Li in the galaxy, see (1975KI14, 1977KI12) and reaction 4 in 7Li. See also (1974KO1C; astrophys.) and 8Be.

5. 6Li(p, γ)7Be Qm = 5.606

Gamma transitions are observed to the ground (γ0) and to the 0.43 MeV (γ1) states. The yield shows no evidence of resonance for Ep = 0.2 to 1.0 MeV and the branching ratio remains approximately constant at (62 ± 5)% to the ground state, 38% to 7Be*(0.43), < 4% to 7Be*(4.57): see (1974AJ01).

6. (a) 6Li(p, p)6Li Eb = 5.606
(b) 6Li(p, 2p)5He Qm = -4.59
(c) 6Li(p, pα)2H Qm = -1.4735

Measurements of elastic angular distributions have been reported for Ep = 0.5 to 600 MeV: see (1966LA04, 1974AJ01) and 6Li. Two resonances are reported at Ep = 1.84 and 5 MeV in the elastic yield [7Be*(7.21, 9.9)]. The parameters of the lower resonance are shown in Table 7.4 (in PDF or PS) (1963MC09). The 5 MeV resonance has Γ ≈ 1.8 MeV and appears to also be formed by p-waves: γ2p is then 3 ± 2 MeV · fm. A weak rise near Ep = 8 to 9 MeV may indicate a further level, 7Be* ≈ 13 MeV (1963HA53). A broad resonance at Ep = 14 MeV is suggested by (1977NE1A). Polarization measurements have been carried out for Ep = 1.2 to 155 MeV [see (1974AJ01)], at Ep-bar = 32 MeV (1976MO1B: p1, p2). A phase shift analysis for Ep = 0.5 to 5.6 MeV shows that only 2S, 4S and 4P are involved. The 4P5/2 phase resonates at Ep = 1.8 MeV, and the broad resonance at 5 MeV can be reproduced equally well by either 4P3/2 or 4P1/2: tensor polarization measurements are necessary to distinguish between the two (1969PE22). An R-matrix analysis of the 2F5/2 state at Ex = 6.73 MeV is reported by (1976DO1B).

The reaction cross section for formation of 6Li*(2.19) has been measured for Ep = 3.6 to 9.40 MeV: a broad resonance indicates the presence of a state with Ex ≈ 10 MeV, Γ = 1.8 MeV, Jπ = (3/2, 5/2)-, T = 1/2 (1967HA07, 1967HA08). The cross-section and angular distributions of p2 (6Li*(3.56)) for Ep = 4.26 to 9.40 MeV is analyzed in terms of two Jπ = 3/2- states at Ex ≈ 10 and 11 MeV: see reaction 3 (1967HA07, 1967HA08). The total cross section for formation of 6Li*(3.56) decreases slowly with energy for Ep = 24.3 to 46.4 MeV (1968AU06). The reaction cross section has been measured for Ep = 25.0 to 48 MeV by (1976SO1B).

For reaction (b) see 5He and (1977NA16). For reaction (c) see 6Li and the polarization measurements of (1974DU10) and (1976DU1C) at Ep = 40 and 19.4 MeV, respectively. See also (1977FR1F, 1978FR1D), (1977MC1C; applied) and (1975BA05, 1977BI1E, 1978MA37; theor.).

7. 6Li(p, n)6Be Qm = -5.070 Eb = 5.606

The yield of neutrons increases approximately monotonically from threshold to Ep = 14.3 MeV (1964BA16). For polarization measurements at Ep = 30 and 50 MeV, see (1969RO20). See also 6Be.

8. 6Li(p, d)5Li Qm = -3.44 Eb = 5.606

See 5Li.

9. 6Li(p, α)3He Qm = 4.0201 Eb = 5.606

Over the range Ep = 25 to 50 keV, the cross section rises from 0.8 to 72 μb: in the formula σ ≈ E-1e-B/√E(square root of E), B = 90 ± 6 keV1/2 (1967FI05). Cross-section measurements for Ep = 62 to 188 keV show deviation from an s-wave Gamow plot above ≈ 130 keV (1966GE11). Using cross-section measurements at Ep = 151 and 317 keV, as well as the (1966GE11) data (1971SP05) calculate S(0) = 3.0 MeV · b. See also (1978EL1A: Ep = 0.1 to 1.0 MeV).

At higher energies the cross section exhibits a broad, low maximum near Ep = 1 MeV and a pronounced resonance at Ep = 1.85 MeV (1951BA79, 1956MA91) and (1977LI01: Γ < 0.5 MeV; Ep = 1.0 to 2.6 MeV). No other structure is reported up to Ep = 5.6 MeV: see (1974AJ01). Measurements between Ep = 0.4 and 3.4 MeV show that the polarizations are generally large and positive. The Ep = 1.9 MeV resonance appears in A1 and A2 (1968BR18).

Angular distributions have been reported for Ep = 0.15 to 16 MeV [see (1974AJ01)] and at Ep = 0.5 to 1.82 MeV (1974JO08), 1.0 to 2.0 MeV (1977LI01), 25.5 to 45 MeV (1974SC24) and 45 MeV (1971BR12). Angular distributions at Ep = 8 to 18.5 MeV have been analyzed using a finite-range multi-interaction DWBA formalism. The analysis leads to reduced widths of 0.69 for α + d in a relative s-state, 0.04 for α + d in a relative d-state and 0.44 for 3He + t in a relative s-state (1973WE07). A polarization measurement is reported at E(6Li) = 16.8 MeV (1976FI1B).

See (1971BR12) for a discussion of the search for excited states of 3He. See also (1974VA1B), (1978PR1B; applied) and (1973LI23, 1975CL1C, 1975WI1C; theor.).

10. 6Li(d, n)7Be Qm = 3.382

Angular distributions of the n0 and n1 groups have been measured at Ed = 0.24 to 3.5 MeV [see (1974AJ01)] and at Ed = 0.204 to 0.873 MeV (1977EL09) and 15.25 MeV (1975AZ02).

The n-γ correlations are isotropic, indicating Jπ = 1/2- for 7Be*(0.43) (1956NE13). Broad maxima are observed in the ratio of low-energy to high-energy neutrons at Ed = 4.2 and 5.1 MeV [7Be*(6.5, 7.2), Γc.m. = 1.2 and 0.5 MeV, respectively] (1957SL01). See also (1974MCZS, 1975MC02, 1977GL05) in 8Be.

11. 6Li(3He, d)7Be Qm = 0.113

Angular distributions of the d0 and d1 groups to 7Be*(0, 0.43) have been measured at Ed = 8, 10, 14 and 18 MeV: all the distributions show an l = 1 maximum at small angles. The DWBA analysis leads to a ratio of spectroscopic factors S*/S [for 7Be*(0.43)/7Be(0)] = 1.55, in fair agreement with other measurements (1968LU02).

12. 6Li(α, t)7Be Qm = -14.208

Angular distributions of t0, t1 and t2 have been reported at Eα = 40 to 46 MeV: see (1974AJ01). [Some of the reported work is unpublished.]

13. 6Li(6Li, αn)7Be Qm = 1.908

See (1977RU06) and 12C in (1980AJ01).

14. 7Li(p, n)7Be Qm = -1.644

Ethresh. = 1880.59 ± 0.08 keV [recommended by (1970RO07)]. The excitation energy of 7Be*(0.43) is 429.20 ± 0.10 keV (1972BO02); τm = 192 ± 25 fsec (1966PA11). [(1976DO10) report 136 ± 10 fsec.] Angular distributions are reported at Ep = 1.9 to 50 MeV [see (1974AJ01)] and at 2.1 to 3.8 MeV (1974BU16: n0), 3.1 to 4.9 MeV (1976BR1E: n1), 14.9 and 17.8 MeV (1974AR05: n0, n1 (not resolved at the lower energy)), 15.1 to 26 MeV (1976PO06: n0, n1), and 24.8, 35.0 and 45.0 MeV (1977SC37: n0, n1). (1976PO06) also report the population of 7Be*(4.55, 6.51, 7.19, 10.79). See also (1977RI07: Ep = 800 MeV) and (1974AJ01).

See also (1976RO10, 1977LO10), (1973RY03, 1974JA1M, 1976NE1B, 1976WA1E, 1978GO1E; applied), (1977ME1C; theor.) and 8Be.

15. 7Li(3He, t)7Be Qm = -0.880

Angular distributions have been measured at E(3He) = 3.0 to 4.0 MeV (1969OR01: t0, t1). See also (1974AJ01). The width of 7Be*(4.57), Γc.m. = 175 ± 7 keV (1971PI06). See also (1974LO1B).

16. 7Li(6Li, 6He)7Be Qm = -4.369

See (1974AJ01).

17. 9Be(p, t)7Be Qm = -12.083

Angular distributions of tritons have been measured at Ep = 43.7 MeV (1965DE08, 1966CE05, 1968BR23: 7Be*(0, 0.43, 4.57, 6.51, 11.01)) and 46 MeV (1967VE01: 7Be*(0 + 0.43, 4.57, 6.51, 10.69)). The 11 MeV state has Ex = 11.01 ± 0.04 MeV (1968BR23), Γ = 298 ± 25 keV, Jπ = 3/2-, T = 3/2 [the Jπ; T assignments are based on the similarity of the angular distribution to that in the (p, 3He) reaction to 7Li*(11.13)] (1965DE08). The ratio of the cross section for formation of 7Be*(0.43) to that for formation of 7Li*(0.48) [in the (p, 3He) mirror reaction] has been measured for Ep = 14.8 to 27 MeV (1975HA1K).

18. 10B(p, α)7Be Qm = 1.146

Angular distributions have been measured for Ep = 2.8 to 7.0 MeV (1964JE01). See also (1966YO1A), (1974AJ01) and 11C in (1975AJ02).

19. 10B(3He, 6Li)7Be Qm = -2.874

At E(3He) = 30.0 MeV angular distributions have been obtained for the transitions to 7Be*(0, 0.43) + 6Li*(0, 2.19): see (1970DE12, 1972OH01).

20. 10B(α, 7Li)7Be Qm = -16.202

At Eα = 45.6 MeV (1969FO06) have measured the angular distributions of the 7Li and of the 7Be ions, corresponding to the ground state transitions. At a given angle the intensities of the two ions are the same, implying that the wave functions of the ground states of 7Li and 7Be are very similar (1969FO06).

21. 10B(7Li, 10Be)7Be Qm = -1.418

See (1977KO27).

22. 11B(d, 6He)7Be Qm = 11.560

See (1974AJ01).

23. 11B(3He, 7Li)7Be Qm = -7.079

See (1971RO1A).

24. 12C(p, 6Li)7Be Qm = -22.568

Angular distributions have been measured at Ep = 36.0, 40.7, 45.0, 50.0 and 56.8 MeV (1971BR07, 1971HO25; 7Be*(0 + 0.43)) and 51.9 MeV (1976KA14; 7Be*(0, 0.43)). See also (1978KU02; theor.).

25. 12C(d, 7Li)7Be Qm = -17.542

At Ed = 39.8 MeV angular distributions have been measured for the transitions 7Li(0) + 7Be(0), 7Li*(0.48) + 7Be(0), 7Li(0) + 7Be*(0.43) and 7Li*(0.48) + 7Be*(0.43). The ratios of the 7Li(0) and 7Be(0) cross sections show asymmetries exceeding 20% (1971YO06). See also (1974VA1A).

26. 12C(3He, 8Be)7Be Qm = -5.781

Angular distributions have been obtained at E(3He) = 25.5 to 29 MeV (1976PI10: 7Be*(0, 0.43)) and 28 and 30 MeV (1970DE12: 7Be*(0, 0.43)+8Be*(0, 2.9)). See also (1974AJ01), (1976PA07, 1973OG1A), (1974DO03; theor.) and 15O in (1976AJ04).

27. 12C(α, 9Be)7Be Qm = -24.693

At Eα = 42 MeV, angular distributions have been measured to 7Be*(0, 0.43) + 9Be(0) (1972RU03).

28. 13C(p, 7Li)7Be Qm = -20.264

At Ep = 45.0 MeV the angular distribution has been measured for the transition to 7Li(0) + 7Be(0) (1971BR07).

29. 14N(3He, 10B)7Be Qm = -10.027

See (1976RO04).

30. 14N(6Li, 13C)7Be Qm = -1.944

See 13C in (1976AJ04).

31. 16O(p, 10B)7Be Qm = -25.270

See (1974AJ01).

32. 16O(3He, 12C)7Be Qm = -5.576

Angular distributions are reported at E(3He) = 30 MeV (1970DE12: to 12C*(0, 4.4, 7.7, 9.6) + 7Be*(0, 0.43)). See also (1974AJ01).

33. 16O(α, 13C)7Be Qm = -21.207

At Eα = 42 MeV, angular distributions have been obtained for the transitions to 7Be*(0, 0.43) + 13C(0) (1972RU03).

34. 19F(d, 14C)7Be Qm = -7.142

The angular distributions to 7Be*(0 + 0.43) + 14C(0) has been measured at Ed = 14.9 MeV (1967DE03).

35. (a) 19F(3He, 15N)7Be Qm = -2.428
(b) 20Ne(3He, 16O)7Be Qm = -3.145

(1970DE12) have studied at E(3He) = 30 MeV the angular distributions to 15N(0) + 7Be*(0, 0.43) and to 16O*(0, 6.06 + 6.13) + 7Be*(0, 0.43).