Neutron-capture gamma rays below 40 keV

Durner, P.; Egidy, T. von; Hartmann, F. J.

doi:10.1016/0168-9002(89)90869-3

Cited by 22 publications

(2 citation statements)

References 33 publications

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“…Furthermore, the decay radiations of the 17 and 23 keV states to the ground state which were recently published by Durner et al [29] were not seen by us due to a 5 mm Pb absorber in front of the detector. Van Assche et al [28] gave intensities and energies of transitions between 20 and 1000 keV which are in very good agreement with our values.…”

Section: Ivb Level Scheme Of S2vmentioning

confidence: 80%

“…Discrepancies of this scaling behavior in s~V were traced to direct capture contributions. (23) 0.029 (6) 4561-,-,3943 620.16t (34) 0.47 (9) 4494-+3874 m 640.31 (12) 0.053 (11) 5949-~5308 685.942 (32) 0.62 (12) 3386-,2700 692.31 (10) 0.087 (17) 5949-,5256 694.34 (17) 0.118 (24) 5808-,5113 695.98 (20) 0.066 (13) 5256~4561 704.38 (16) 0.043 (9) 5818-~5113 707.76 (14) 0.052 (10) 4225-,3517 746.36 (22) 0.033 (7) 4124-,3378 754.290 (48) 0.206 (41) 762.06 (6) 0.147 (29) 5256--,4494 779.07 (19) 0.043 (9) 4583-*3804 809.37 (9) 0.092 (18) 5256~4447 829.79 (10) 0.092 (18) 5943-+5113 S 5850-,5020 832.590 (30) 2.27 (45) 4447-,3614 868.08 (15) 0.055 (11) 5981-,5113 879.84 (7) 0.144 (29) 4494-,3614 893.50 (9) 0.106 (21) 6297~5404 ~ 5914--+5020 909.72 (24) 0.036 (7) 5404--,4494 926.80 (33) 0.039 (8) 6260-+5333 928.70 (8) 0.163 (33) 5949-~5020 931.72 (31) 0.030 (6) 6265-,-+5333 934.569 (33) 0.80 (16) 6260-,5325 946.8t7 (44) 0.29 (6) 972.62 (8) 0.136 (27) 997.07 (20)…”

Section: E:~ >~ Bn Exmentioning

confidence: 96%

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Complete spectroscopy of51,52V via the50,51V(n, ?) reactions

Michaelsen

Lieb

Robinson

1991

Z. Physik A - Hadrons and Nuclei

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The gamma-ray spectra emitted after thermal neutron capture in highly enriched 5~ and natv targets have been studied using in-pile targets at the ILL high flux reactor and pair and germanium detectors. The neutron binding energies in 51V and 52V were determined to be Bn(51V)=l1051.11(17) keV and Bn(52V) =7311.22(26) keV. The thermal neutron capture cross-section in s~ was measured to be 21_+4 b. From 724 lines attributed to slV, 330 transitions, comprising 90% of the ?-ray flux, were placed into the level scheme. Fifty-nine primary dipole transitions from the 11/2 + or 13/2 + capture states in 51V were established from which the E1 strength distribution was deduced. The energy scaling of these primary transitions was found to follow the El-giant dipole resonance dominance. Many new levels were established; a number of states proposed in previous (d,p) and (n, ?) work were confirmed from their primary population and decaying secondary radiations. The density of levels in the high spin (9/2<_I<_ 15/2) region was parametrized with the Fermi gas model. The spin distributions of 51V were analyzed and a spin cut-off parameter a = 2.8 (3) was deduced. -A nearly complete level scheme of 52V up to 3.5 MeV excitation and similar results concerning the level density and the primary y-ray spectrum were obtained in the 5W (n, ?)52V study. PACS" 21.10.Ma; 23.20.Lv; 25.40.Lw, 27.40. +z I. MotivationIn recent years, "complete" nuclear level schemes have been studied with the aim of testing either specific nuclear models, i.e. to identify all predicted states, or of testing * Supported by Deutsches BMFT under contract 06GO141 ** Present address: Physics Department, Tennessee Technological University, Cockeville, TN 38505, USA statistical (or even chaotic) behavior as visible in the level density distribution, nearest-neighbor level spacings and y-ray strength functions. A test of both aspects appears to be most interesting in nuclei where rather simple rnodels, as for example the shell model, can be assumed or shown to be valid [ 1,2].The present investigation of the s~ y)s~'52V reactions with thermal neutrons was carried out for the following reasons:i) The odd-odd target nucleus 5~ has U= 6 +, leading to spin-parity assignments of either 11/2 + or 13/2 + for the capture state(s) in slV, after s-wave thermal neutron capture. Primary dipole transitions thus populate levels in the spin window 9/2<_1<_15/2. Such high spins are usually not accessible in neutron capture reactions. It was expected that complete spectroscopy in this spin window would allow the measurement of the spin dependence of the level density. ii) Previous (n, y) studies of the G6ttingen-GrenobleMunich collaboration have concentrated on nuclei near the N= 20 and N= 50 neutron shell closures. Krusche, yon Egidy and collaborators [3][4][5] have studied the 4~ isotopes, while Winter et al. [6][7][8] have scanned the isotopes 87"88"89Sr. These experiments gave evidence for shell effects in the level density parameters. Moreover, a comparison of the level den...

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Section: Ivb Level Scheme Of S2vmentioning

confidence: 80%