Gamma ray energies and 36Cl level scheme from the reaction 35Cl(n, γ)

Krusche, B.; Lieb, Klaus; Daniel, H.; Egidy, T. von; Barreau, G.; Börner, H. G.; Brissot, R.; Hofmeyr, C.; Rascher, R.

doi:10.1016/0375-9474(82)90112-9

Cited by 100 publications

(12 citation statements)

References 16 publications

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“…The information obtained from the different spectra is displayed in Table 2. The energy calibration and the relative intensity calibration was determined with 36C1 lines of target 3 by comparison with the values of Krusche et al [14]. These calibrations were transfered via the Eu lines to the other spectra.…”

Section: Discussionmentioning

confidence: 99%

Cross sections and ?-rays from multiple neutron capture in151Eu

1985

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Primary capture gamma rays following multiple neutron capture in 151Eu have been measured as a function of the irradiation time. Neutron capture cross sections of the ~52Eu 3-groundstate and of the 15ZEu 0-isomer (T~/2 =9.3h) were determined. These cross sections are relevant for the interpretation of inelastic scattering of neutrons at isomeric states with energy gain (neutron acceleration). The level scheme of 153Eu has been extended. Neutron binding energies of ~ 5ZEu, 153Eu ' 153Gd and z 54Gd are given.

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Section: Discussionmentioning

confidence: 99%

Cross sections and ?-rays from multiple neutron capture in151Eu

1985

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“…The spectra were both energy-and efficiency-calibrated with respect to the 36C1 standard [15]. This was achieved by first calibrating the 36C1 transitions in the mixed spectra.…”

Section: Discussionmentioning

confidence: 99%

Thermal neutron capture?-ray spectroscopy of59Ni and61Ni

Harder

Michaelsen

Lieb

et al. 1993

Z. Physik A - Hadrons and Nuclei

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Abstract. The 7-radiation emitted after thermal neutron capture in isotopically enriched 58Ni and 6~ was measured at the ILL high flux reactor by means of Ge/NaI detectors operated in Compton suppression and pair spectrometer mode. The neutron binding energies were determined as B.(59Ni) = 8999.15(23) keV and Bn(61Ni) = 7820.07(20) keV; some 95% of the total y-ray fluxes through s9,61Ni were assigned. The y-ray strength functions of the primary transitions and the level densities are discussed. 21.10.Ma; 23.20.Lv; 25.40.Lw; 27.50.+e PACS: MotivationThe 7-ray decay of the capture state(s) populated in thermal neutron capture reactions is considered to be a nonselective process and thus enables one to establish "complete" level schemes up to about half the neutron binding energy B, and within the spin window bound by s-wave capture and primary dipole transitions. Previous detailed studies of light and medium nuclei [1,2] have shown that the assignment of new states is essentially limited by the increasing level density and decreasing phase space of primary transitions, for given capture crosssections and spectrometer resolution and efficiency.Previous (n, ~) studies in the even-mass nickel targets [3] have shown deviations from this behaviour insofar as the primary spectra are dominated by very few strong transitions to low-lying negative-parity states which account for some 70%-90% of the primary flux. This direct mechanism thus dominates the capture process and leaves correspondingly little flux to higher excited states; this flux was not fully resolved up to now. With the high neutron flux available at the ILL reactor and a high resolution pair spectrometer we hoped to be able to identify the missing portions of the primary spectra Supported by Deutsches BMFT of the 5s'6~ 7) reactions, to identify new excited states and make spin-parity assignments. This information, together with the results from charged-particle induced reactions then should allow us to derive level densities and ~-ray strength functions in the semi-magic Z=28 nickel isotopes, and compare them to findings for N ~_ 20, 28 and 50 neutron magic nuclei [4][5][6][7][8][9].This present work complements our previous studies of the 6~Ni(n, ~)63Ni and 6ZNi(2 n, 7)64Ni reactions [10] and the GRID lifetime measurements in 59'61Ni by U1-big et al. [11]. In this latter work, assumptions concerning the feeding mechanism of several excited states had to be inferred which now can be checked with the present data. Ulbig and co-authors [11,12] also performed extensive shell model calculations of the negative parity states in 59Ni. Experimental procedureThe experimental procedure followed the method applied in our previous neutron capture studies on 31p, s~ 86'87'aasr and 62Ni targets [5-8, 10, 13] where further details of the experimental set-up and data analysis are given. First the 58Ni target, consisting of ca. 130mg of metallic powder (isotopical enrichment 99.8%), was exposed to a thermal neutron flux of 5.5.1014 neutrons/cm 2 s near the core of the ILL h...

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“…The respective capture cross-sections in the three relevant isotopes are o_(50V)=21_2 b+4 (see below), r (51V) = 4.9 (1) b and r (35C1) = 43.6 b [22], leading to ),-ray fluxes in Slv, 52V and 36C1 in the ratio of 1:100:75. These spectra contain nearly equal numbers of intense 52V and 36C1 transitions and permitted energy and efficiency calibration of the Ge-and pair-spectrometer with respect to the 36C1 standard [23]. As the neutron binding energy in 52V is similar to that of 36C1, the full energy range of the 36C1 lines was sufficient for this calibration.…”

Section: Methodsmentioning

confidence: 98%

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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Gamma ray energies and 36Cl level scheme from the reaction 35Cl(n, γ)

Cited by 100 publications

References 16 publications

Cross sections and ?-rays from multiple neutron capture in151Eu

Cross sections and ?-rays from multiple neutron capture in151Eu

Thermal neutron capture?-ray spectroscopy of59Ni and61Ni

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

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