Thermal-neutron cross sections and resonance integrals of

The thermal-neutron capture cross sections and resonance integrals of 138Ba(n,$\gamma$)139Ba and 141Pr(n,$\gamma$)142Pr were measured by activation method using an isotopic Am-Be neutron source. The estimations were with respect to that of 55Mn(n,$\gamma$)56Mn and 197Au(n,$\gamma$)198Au reference monitors. The measured thermal-capture cross section of 138 Ba with respect to 55 Mn is 0.410±0.023 b and with respect to 197 Au is 0.386±0.019 b. The measured thermal-capture cross section of 141 Pr with respect to 55 Mn is 11.36±1.29 b and with respect to 197 Au is 10.43±1.14 b. The resonance integrals for 138 Ba are 0.380±0.033 b (55 Mn) and 0.364±0.027 b (197 Au) and for 141 Pr are 21.05±2.88 b (55 Mn) and 15.27±1.87 b (197 Au). The comparison between the present measurements and various reported values are discussed. The cross sections corresponding to the selected isotopes are measured using an Am-Be source facility for the first time

Thermal neutron capture cross-section and resonance integral measurements of

Thermal neutron capture cross-sections and resonance integrals of 139La(n,$\gamma$)140La and 140Ce (n,$\gamma$)141Ce are measured with respect to reference reactions 197Au(n,$\gamma$)198Au and 55Mn(n,$\gamma$)56Mn using the neutron activation technique. Measurements are carried out using neutrons from an Am-Be source located inside a concrete bunker. Two different methods are used for determining self-shielding factors of activation foils as well as for finding the epithermal neutron spectrum shape factor. For 139 La with reference to 197 Au and 55 Mn the measured thermal cross sections are $9.24 \pm 0.25$ b and $9.28 \pm 0.37$ b, respectively, while the measured resonance integrals are $12.18 \pm 0.67$ b and $11.81 \pm 0.94$ b, respectively. For 140 Ce with reference to 197 Au and 55 Mn the measured thermal cross sections are $0.44 \pm 0.01$ b and $0.44 \pm 0.02$ b, respectively, while the measured resonance integrals are $0.55 \pm 0.03$ b and $0.54 \pm 0.04$ b, respectively. The present measurements are compared with earlier measurements and evaluations. Presently estimated values confirm the established 139La(n,$\gamma$)140La cross-sections. The presently measured thermal capture cross-section 140Ce(n,$\gamma$)141Ce , though lower than the evaluated data, is having higher accuracy compared to previous measurements with large uncertainties. The resonance integral measured is higher (like most previous measurements) than most evaluations requiring a revision of the evaluated data

Covariance analysis on the thermal neutron capture cross sections using an Am-Be neutron source

We measured the thermal cross sections of 71Ga(n, γ)72Ga using an Am-Be neutron source having strength of 4 × 107 neutrons/sec using the two monitor reactions 197Au(n, γ)198Au and 55Mn(n, γ)56Mn, and obtained 4.07±0.27 b and 3.97±0.31 b as the values measured relative to Au and Mn neutron captures, respectively. We constructed their covariance matrix by taking into account the correlation of parameters which are not independent in derivation of these two thermal cross sections (e.g., Ga sample weight, decay data of 72Ga, detector efficiency of γ -ray emitted from 72Ga). The off-diagonal weighted mean of the two cross sections 4.04±0.27 b was derived from the two thermal cross sections and their covariance matrix

Covariance analysis on the thermal neutron capture cross sections using an Am-Be neutron source

We measured the thermal cross sections of 71Ga(n, γ)72Ga using an Am-Be neutron source having strength of 4 × 107 neutrons/sec using the two monitor reactions 197Au(n, γ)198Au and 55Mn(n, γ)56Mn, and obtained 4.07±0.27 b and 3.97±0.31 b as the values measured relative to Au and Mn neutron captures, respectively. We constructed their covariance matrix by taking into account the correlation of parameters which are not independent in derivation of these two thermal cross sections (e.g., Ga sample weight, decay data of 72Ga, detector efficiency of γ -ray emitted from 72Ga). The off-diagonal weighted mean of the two cross sections 4.04±0.27 b was derived from the two thermal cross sections and their covariance matrix

Measurement of thermal neutron capture cross section of

The thermal neutron cross section of 71Ga(n,$\gamma$)72Ga reaction was measured with respect to the 197Au(n,$\gamma$)198Au and 55Mn(n,$\gamma$)56Mn monitor reactions using neutrons from an Am-Be source placed inside a concrete bunker. A covariance analysis was performed to obtain the off-diagonal weighted mean of the results determined with the two monitor reactions. The thermal neutron cross section obtained in the present study is $4.05 \pm 0.27$ b. The present result is lower than the data measured under neutron fields having broad neutron spectra in general, but more consistent with the thermal neutron cross sections extrapolated from the cross sections measured under monoenergetic neutron fields according to the $1/v$ -law. The current status of the 71Ga(n,$\gamma$)72Ga reaction cross section in the nuclear databases is briefly reviewed in the relation with the Maxwellian spectrum averaged cross section for s -process calculation