Energy Levels of Light Nuclei. V

Abstract

1. He'(m m)He': E""=0. 95 (center of mass); mass defect = 12.92~0.05. 2. Li'(1 o)Hes: He'=He'+v+0. 97+0.05; mass defect = 12.94~0.05. 3. Li'(d He')He'. Qs --0.91&0. 09;mass defect= 12.85 0.09. 4. Li'(d o)He'. Qs --14.23&0.07; mass defect= 12.85 0.07. We adopt: He' mass defect=12. 92&0.08 Mev. I. (a) H'(d n)He4 Q =17.577 Zs 16. 63--(b) H'(1 e)He4The yield exhibits a pronounced maximum near E~=107 kev, with a cross section of 4.95&0.14 b (Ar 54) t Lsee also (Aj 52c)). Precise cross sections in the tange 8&=10 to 1700 kev are tabulated by (Ar 52d), ' E. P. Wigner and L. Eisenbud, Phys. Rev. 72, 29 (1947); T.Teichmann and E. P. Wigner, Phys. Rev. 87, 123 (1952).f' References are indicated by the erst two letters of the 6rst named author and are listed at the end of the article. VIII. Li6(y t)He' Q = -15.786 This reaction has not been observed with 17.6-Mev gammas. The cross section is &6&4pb (Ti 54b). Ix. Li~(e g')Li6 See Li'. Li'(e e')Li'. X. (a) Li'(p p')Li'* (b) Li'(d d')Li'* Proton and deuteron groups are observed corresponding to the state at 2.19 Mev. At Eq= 7.4 Mev (|I = 90'), no deuteron group corresponding to the presumed T= 1 state at 3.57 Mev is observed [(Br53h) and C. P. Browne, private communication). See also (Aj 52c). ENERGY LEVELS OF LIGHT NUCLEI Lie, Be6 He7, Li7XI. Li'(p d)Li' Q"= -5.010Deuteron groups have been observed corresponding to the ground state, and to levels at 2.2&0.2 and 3.7 &0.2 Mev (Fr 52). At E"=18 Mev, angular distributions of the deuterons to the ground state and the 2.19-Mev level, analyzed by pickup theory, indicate l"=1 and hence even parity, 7 &3, for both states (Re 54a).XII. Li'(d t)Li' Q = -0.988The angular distributions of the tritons, analyzed by pickup theory, indicates l"=1, and hence even parity for the ground state (Ho 53c, Le 54) and for the 2.19-Mev state (Le 54). At Eq 14.5 M-ev, the cross sections Ka

The Photoneutron Cross Section of 9Be in the Intermediate Energy Range

“…Figure 4 shows the cross section curve plotted beside an energy level diagram (from Ajzenberg and Lauritsen 1955). Since Ajzenberg and Lauritsen's review paper, Almqvist, Allen, and Bigham (1955) have reported a previously unobserved level at 9·2 MeV.…”

“…A summary of these experiments is given by . Ajzenberg and Lauritsen (1955). Experiments on the photodisintegration of DBe have, with one exception, used monochromatic.…”

A Search for Levels of 7Li Between 9·0 and 9·55 MeV Excitation

“…In the experiments reported here, the cross section of 6Li(n,3H)4He was measured, with good energy resolution, over a neutron energy range 2 ·0-2 . 65 MeV; this corresponds to an excitation of the compound 7Li system from 9·0 to 9 ·55 MeV where a fairly well-established level of 7Li is known to be present (Ajzenberg and Lauritsen 1955). From a knowledge of the neutron and triton partial widths which have been established for this level by y-ray absorption experiments it would appear that, to an order of magnitude, the resonance cross section to this level by neutron absorption in 6Li should be several hundred millibarns.…”

Photodisintegration of 16O and 63Cu by Photons of Variable Energy

“…The 7Li(p, r)8Be reaction has a Q-value of 17 ·242 MeV (Ajzenberg and Lauritsen 1955). The ground state of 8Behas a width of a few electron-volts, which is small enough to be ignored, and so the photons from transitions to the ground state have energy given by (1).…”

“…160(y, n) 15 0 EXPERIMENT Because of the small cross section of this reaction and the low intensity of y-radiation available, it was necessary to detect the 15 0 produced with the highest possible efficiency. This was done by counting the 1·68 MeV positrons emitted by 15 0, the half-life of which is 118 sec (Ajzenberg and Lauritsen 1955). 47t geometry was obtained by making a scintillation counter in which the scintillator itself was rich' in oxygen.…”