Thermal Neutron Capture Cross Sections Of The Palladium Isotopes

Abstract

Abstract.We have measured precise thermal neutron capture γ-ray cross sections σ γ for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF) [1]. Total radiative neutron capture cross-sections σ 0 can be deduced from the sum of transition cross sections feeding the ground state of each isotope if the decay scheme is complete. The Palladium isotope decay schemes are incomplete, although transitions deexciting low-lying levels are known for each isotope. We have performed Monte Carlo simulations of the Palladium thermal neutron capture de-excitation schemes using the computer code DICEBOX [2]. This program generates a level scheme where levels below a critical energy E crit are taken from experiment, and those above E crit are calculated by a random discretization of an a priori known level density formula ρ(E, J π ). Level de-excitation branching intensities are taken from experiment for levels below E crit and the capture state, or calculated for levels above E crit assuming an a priori photon strength function and applying allowed selection rules and a Porter-Thomas distribution of widths. The calculated feeding to levels below E crit can then be normalized to the measured cross section deexciting those levels to determine the total radiative neutron cross-section σ 0 . In this paper we have measured σ 0 [ 102 Pd(n,γ)]=0.9±0. We have also determined from our statistical calculations that the neutron capture state in 107 Pd is best described as 2 + (60%)+3 + (40%). Agreement with literature values was excellent in most cases. We found significant discrepancies between our results for 102 Pd and 110 Pd and earlier values that could be resolved by re-evaluation of the earlier results.

Thermal Neutron Capture Cross Section of Palladium-107

“…Summation of their intensities yields a lower limit for 0 , i.e., 1998 20:0 AE 3:0 JENDL-3.3 8) 2002 20.25 Mughabghab 9) 2003 21:0 AE 1:5 Firestone et al 14) 2005 21:1 AE 1:5 a) Present result 19:1 AE 0:5 a)…”

“…Our measured 0 for 105 Pd is compared to a previous measurement and evaluations in Table 3. Recently, Firestone et al 14) measured the 0 values for all stable Pd isotopes at the Budapest Reactor using the guided thermal neutron beam. Their result for 105 Pd agrees with the value we determined within the reported uncertainties, lending confidence to our result for 107 Pd.…”

A bulk silicon micromachined structure for gas microdischarge-based detection of beta-particles

“…The micro-detector performance was compared to a commercial general-purpose beta monitor (RPI, Radmonitor: GM1) using a 0.1 µCi source of 90 Sr at a distance of 5 cm. As a rule of thumb, the average beta energy can be roughly estimated by [25] More rigorously calculated values for the average beta energies of 90 Sr and 90 Y are 196.4 keV and 935.3 keV, respectively [28]. The calculated dose rate under these conditions (assuming 90 Sr and 90 Y are in equilibrium) is 13.5 mRad h −1 .…”

“…Since the parameter n is difficult to calculate for materials with complex compositions such as Pyrex glass, this value was estimated by fitting the theoretical estimate with reference data given in [27]. The beta energy spectra for 90 Sr/ 90 Y and 204 Tl are shown in figure 2(a) [28]. It is based on theoretical data and is accurate except at very low energies.…”

“…Using the beta energy spectrum and the energy attenuation through the glass intercavity attenuator, the count ratio can be estimated. The assumptions and [28,29]. (b) Theoretical estimate of stopping power as a function of beta energy through glass.…”