@article{krticka_firestone_mcnabb_sleaford_agvaanluvsan_belgya_revay_2008, title={Thermal neutron capture cross sections of the palladium isotopes}, volume={77}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.77.054615}, abstractNote={Precise thermal neutron capture \ensuremath{\gamma}-ray cross sections ${\ensuremath{\sigma}}_{\ensuremath{\gamma}}$ were measured for all elements with $Z=1\text{\ensuremath{-}}83,90$, and 92, except for He and Pm, at the Budapest Reactor. These data were evaluated with additional information from the literature to generate the Evaluated Gamma-ray Activation File (EGAF). Isotopic radiative neutron cross sections can be deduced from the total transition cross section feeding the ground state, ${\ensuremath{\sigma}}_{0}=\ensuremath{\Sigma}{\ensuremath{\sigma}}_{\ensuremath{\gamma}}(\mathrm{GS})$ if the decay scheme is complete. The EGAF file contains partial \ensuremath{\gamma}-ray cross sections for all stable palladium isotopes. None of these decay schemes are complete, although in each case transitions de-exciting low-lying levels are known. We have performed Monte Carlo simulations of the palladium thermal neutron capture decay schemes using the computer code DICEBOX. The simulated populations of low low-lying levels are normalized to the measured ${\ensuremath{\sigma}}_{\ensuremath{\gamma}}$ values from EGAF and the total radiative neutron cross section ${\ensuremath{\sigma}}_{0}$ is obtained. The ${\ensuremath{\sigma}}_{0}$ values derived for the palladium isotopes agree well with previous measurements and were in several cases more precise. Complementary use of \ensuremath{\gamma}-ray cross-section data and Monte Carlo calculations has proven effective in determining both the palladium total radiative cross sections and new nuclear structure information.}, number={5}, journal={PHYSICAL REVIEW C}, author={Krticka, M. and Firestone, R. B. and McNabb, D. P. and Sleaford, B. and Agvaanluvsan, U. and Belgya, T. and Revay, Z. S.}, year={2008}, month={May} }
 @article{krticka_becvar_tomandl_rusev_agvaanluvsan_mitchell_2008, title={Two-step gamma cascades following thermal neutron capture in Mo-95}, volume={77}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.77.054319}, abstractNote={A strong enhancement of the photon strength function at low {gamma}-ray energies was recently reported for several Mo isotopes. To study this enhancement further we have measured the spectra of two-step {gamma} cascades following thermal neutron capture in {sup 95}Mo. These spectra were compared with simulations of the {gamma} decay of {sup 96}Mo performed with the aid of the dicebox algorithm. Simulations with a large number of model combinations of photon strength functions for E1,M1, and E2 radiation are not consistent with the strong enhancement observed in the {sup 96}Mo({sup 3}He,{sup 3}He{sup '}{gamma}){sup 96}Mo and {sup 97}Mo({sup 3}He,{alpha}{gamma}){sup 96}Mo reactions. Predictions based on a combination of E1,M1, and E2 photon strength functions with no enhancement of the photon strength functions at low {gamma}-ray energies are in good agreement with the two-step {gamma} cascade data.}, number={5}, journal={PHYSICAL REVIEW C}, author={Krticka, M. and Becvar, F. and Tomandl, I. and Rusev, G. and Agvaanluvsan, U. and Mitchell, G. E.}, year={2008}, month={May} }
 @article{algin_schiller_voinov_agvaanluvsan_belgya_bernstein_brune_chankova_garrett_grimes_et al._2007, title={Bulk properties of iron isotopes}, volume={70}, ISSN={["1562-692X"]}, DOI={10.1134/S1063778807090232}, abstractNote={Nuclear level densities and radiative strength functions (RSFs) in 56Fe and 57Fe were measured using the 57Fe(3He, αγ) and 57Fe(3He, 3He′γ) reactions, respectively, at the Oslo Cyclotron Laboratory. A low-energy enhancement in the RSF below 4-MeV energy was observed. This finding cannot be explained by common theoretical models. In a second experiment, two-step cascade intensities with soft primary transitions from the 56Fe(n, 2γ) reaction were measured. The agreement between the two experiments confirms the low-energy enhancement in the RSFs. In a third experiment, the neutron evaporation spectrum from the 55Mn(d, n)56Fe reaction was measured at 7-MeV deuteron energy at the John Edwards Accelerator Laboratory at Ohio University. Comparison of the level density of 56Fe obtained from the first and third experiments gives an overall good agreement. Furthermore, observed enhancement for soft γ rays is strengthened by the last experiment.}, number={9}, journal={PHYSICS OF ATOMIC NUCLEI}, author={Algin, E. and Schiller, A. and Voinov, A. and Agvaanluvsan, U. and Belgya, T. and Bernstein, L. A. and Brune, C. R. and Chankova, R. and Garrett, P. E. and Grimes, S. M. and et al.}, year={2007}, month={Sep}, pages={1634–1639} }
 @article{dashdorj_kawano_garrett_becker_agvaanluvsan_bernstein_chadwick_devlin_fotiades_mitchell_et al._2007, title={Effect of preequilibrium spin distribution on Ti-48+n cross sections}, volume={75}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.75.054612}, abstractNote={Nuclear model calculations of discrete {gamma}-ray production cross sections produced in {sup 48}Ti(n,n{sup '}{gamma}{sub i}){sup 48}Ti and {sup 48}Ti(n,2n{gamma}{sub i}){sup 47}Ti reactions were made as a function of incident neutron energy from E{sub n}=1 MeV to 35 MeV and compared with new experimental results using the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE) at LANSCE. The Hauser-Feshbach reaction code GNASH, incorporating the spin distribution for the preequilibrium process calculated with the Feshbach-Kerman-Koonin (FKK) quantum-mechanical preequilibrium theory, was used to calculate partial {gamma}-ray transition cross sections. The comparisons of calculated and experimental data demonstrate that, the FKK model for preequilibrium leads a better overall reproduction of the experimental data above E{sub n}=10 MeV, where preequilibrium processes are important. The FKK calculation predicts a strong reduction in the high-spin state population in {sup 48}Ti by inelastic scattering. Population of low-spin states was also affected, however the change in the low-lying 983.5-keV (2{sup +}) state production is small because almost all {gamma}-ray decay cascades feed this transition. In addition, the FKK calculation has a significant impact on the partial {gamma}-ray transition cross sections for the (n,2n) reaction above E{sub n}=15 MeV. The calculated cross sections for high-spin states in {sup 47}Timore » are reduced, and those from the low-spin states are enhanced, in agreement with the experimental cross section data.« less}, number={5}, journal={PHYSICAL REVIEW C}, author={Dashdorj, D. and Kawano, T. and Garrett, P. E. and Becker, J. A. and Agvaanluvsan, U. and Bernstein, L. A. and Chadwick, M. B. and Devlin, M. and Fotiades, N. and Mitchell, G. E. and et al.}, year={2007}, month={May} }
 @article{dashdorj_mitchell_kawano_becker_agvaanluvsan_chadwick_cooper_devlin_fotiades_garrett_et al._2007, title={Neutron induced inelastic cross-sections of Sm-150 for E-n=1-35 MeV}, volume={261}, ISSN={["1872-9584"]}, DOI={10.1016/j.nimb.2007.04.161}, abstractNote={Cross-section measurements were made of prompt γ-ray production as a function of incident neutron energy (En = 1–35 MeV) on an enriched (95.6%) l50Sm sample. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the Los Alamos Neutron Science Center (LANSCE) facility. The prompt-reaction γ-rays were detected with the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The γ-ray excitation functions were converted to partial γ-ray cross-sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). Partial γ-ray cross-sections were predicted using the Hauser–Feshbach statistical reaction code GNASH. Above En ∼ 8 MeV, the pre-equilibrium reaction process dominates the inelastic reaction. The spin-distribution transferred in pre-equilibrium neutron induced reactions was calculated using the quantum mechanical theory of Feshbach, Kerman and Koonin (FKK). These pre-equilibrium spin distributions were incorporated into a new version of GNASH and the γ-ray production cross-sections were calculated and compared with experimental data. The difference in the partial γ-ray cross-sections using spin-distributions with and without pre-equilibrium effects is discussed.}, number={1-2}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}, author={Dashdorj, D. and Mitchell, G. E. and Kawano, T. and Becker, J. A. and Agvaanluvsan, U. and Chadwick, M. B. and Cooper, J. R. and Devlin, M. and Fotiades, N. and Garrett, P. E. and et al.}, year={2007}, month={Aug}, pages={948–952} }
 @article{kaneko_hasegawa_agvaanluvsan_algin_chankova_guttormsen_larsen_mitchell_rekstad_schiller_et al._2006, title={Breaking of nucleon Cooper pairs at finite temperature in Mo93-98}, volume={74}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.74.024325}, abstractNote={The S shape of the canonical heat-capacity curve is known as a signature of the pairing transition, and along an isotopic chain it is significantly more pronounced for nuclei with an even number of neutrons than for those with an odd number. Although the heat capacities extracted from experimental level densities in {sup 93-98}Mo exhibit a clear S shape, they do not show such an odd-even staggering. To understand the underlying physics, we analyze thermal quantities evaluated from the partition function calculated using the static-path plus random-phase approximation (SPA+RPA) in a monopole pairing model with number-parity projection. The calculated level densities reproduce very well the experimental data, and they also agree with estimates made using the back-shifted Fermi-gas model. We clarify the reason why the heat capacities for Mo isotopes do not show odd-even staggering of the S shape. We also discuss thermal odd-even mass differences in {sup 94-97}Mo that were calculated using the three-, four-, and five-point formulas. These thermal mass differences are regarded as indicators of pairing correlations at finite temperature.}, number={2}, journal={PHYSICAL REVIEW C}, author={Kaneko, K. and Hasegawa, M. and Agvaanluvsan, U. and Algin, E. and Chankova, R. and Guttormsen, M. and Larsen, A. C. and Mitchell, G. E. and Rekstad, J. and Schiller, A. and et al.}, year={2006}, month={Aug} }
 @article{chankova_schiller_agvaanluvsan_algin_bernstein_guttormsen_ingebretsen_lonnroth_messelt_mitchell_et al._2006, title={Level densities and thermodynamical quantities of heated Mo93-98 isotopes}, volume={73}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.73.034311}, abstractNote={Level densities for {sup 93-98}Mo have been extracted using the ({sup 3}He,{alpha}{gamma}) and ({sup 3}He,{sup 3}He{sup '}{gamma}) reactions. From the level densities thermodynamical quantities such as temperature and heat capacity can be deduced. Data have been analyzed by utilizing both the microcanonical and the canonical ensemble. Structures in the microcanonical temperature are consistent with the breaking of nucleon Cooper pairs. The S shape of the heat capacity curves found within the canonical ensemble is interpreted as consistent with a pairing phase transition with a critical temperature for the quenching of pairing correlations at T{sub c}{approx}0.7-1.0MeV.}, number={3}, journal={PHYSICAL REVIEW C}, author={Chankova, R and Schiller, A and Agvaanluvsan, U and Algin, E and Bernstein, LA and Guttormsen, M and Ingebretsen, F and Lonnroth, T and Messelt, S and Mitchell, GE and et al.}, year={2006}, month={Mar} }
 @article{agvaanluvsan_algin_becker_guttormsen_mitchell_siem_schiller_voinov_2005, title={Investigation of the radiative strength function}, volume={241}, ISSN={["0168-583X"]}, DOI={10.1016/j.nimb.2005.07.081}, abstractNote={The radiative strength function (RSF) is key for understanding nuclear reaction rates in areas ranging from astrophysics to radiochemical diagnostics. The RSF also provides a tool for understanding the characteristics of gamma-ray cascades. Unresolved transitions in nuclear deexcitation processes are best described by statistical properties such as the radiative strength function. The sequential extraction method developed at the Oslo Cyclotron Laboratory provides data for radiative strength functions for gamma-ray energies from 1 MeV to the neutron binding energy. The data are averaged over about 100 keV energy bin and normalized to the average total radiative width of neutron resonances. The radiative strength functions in all nuclei studied show a characteristic increase with increasing gamma-ray energy. However, the detailed structures in the radiative strength function for various nuclei show different behavior in various mass regions. In rare-earth nuclei, a resonance structure near 3 MeV is observed. For several lighter nuclei (A < 100), a large enhancement for low transition energies is observed. This unexpected phenomenon is not explained by existing theoretical models. Additional investigations using independent measurements are underway. The experiments and analysis methods will be described briefly. Experimental data for Fe, Sn, and Yb will be shown to illustrate the variety of behavior observed for the radiative strength function.}, number={1-4}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}, author={Agvaanluvsan, U and Algin, E and Becker, JA and Guttormsen, M and Mitchell, GE and Siem, S and Schiller, A and Voinov, A}, year={2005}, month={Dec}, pages={180–184} }
 @article{siem_agavaanluvsan_mitchell_al._2005, title={Soft resonances in hot nuclei}, volume={36}, number={4}, journal={Acta Physica Polonica. B}, author={Siem, S. and Agavaanluvsan, U. and Mitchell, G. and al.}, year={2005}, pages={1089–1093} }
 @article{voinov_algin_agvaanluvsan_belgya_chankova_guttormsen_mitchell_rekstad_schiller_siem_2004, title={Large enhancement of radiative strength for soft transitions in the quasicontinuum}, volume={93}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.93.142504}, abstractNote={Radiative strength functions (RSFs) for the (56,57)Fe nuclei below the separation energy are obtained from the 57Fe(3He,alphagamma)56Fe and 57Fe(3He,3He'gamma)57Fe reactions, respectively. An enhancement of more than a factor of 10 over common theoretical models of the soft (E(gamma) less than or approximately equal 2 MeV) RSF for transitions in the quasicontinuum (several MeV above the yrast line) is observed. Two-step cascade intensities with soft primary transitions from the 56Fe(n,2gamma)57Fe reaction confirm the enhancement.}, number={14}, journal={PHYSICAL REVIEW LETTERS}, author={Voinov, A and Algin, E and Agvaanluvsan, U and Belgya, T and Chankova, R and Guttormsen, M and Mitchell, GE and Rekstad, J and Schiller, A and Siem, S}, year={2004}, month={Oct} }
 @article{agvaanluvsan_schiller_becker_bernstein_garrett_guttormsen_mitchell_rekstad_siem_voinov_et al._2004, title={Level densities and gamma-ray strength functions in Yb-170,Yb-171,Yb-172}, volume={70}, number={5}, journal={Physical Review. C, Nuclear Physics}, author={Agvaanluvsan, U. and Schiller, A. and Becker, J. A. and Bernstein, L. A. and Garrett, P. E. and Guttormsen, M. and Mitchell, G. E. and Rekstad, J. and Siem, S. and Voinov, A. and et al.}, year={2004} }
 @article{agvaanluvsan_mitchell_shriner_pato_2003, title={Parity dependence of nuclear level densities}, volume={67}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.67.064608}, abstractNote={High resolution proton resonance data have been examined for a possible parity dependence of nuclear level densities. Five spin-parity ${\mathrm{combinations}\mathrm{---}1/2}^{+},$ ${1/2}^{\ensuremath{-}},$ ${3/2}^{\ensuremath{-}},$ ${3/2}^{+},$ and ${5/2}^{+}$---have been analyzed for three ${\mathrm{datasets}\mathrm{---}}^{44}\mathrm{Ca}(p,p),$ ${}^{48}\mathrm{Ti}(p,p),$ and ${}^{56}\mathrm{Fe}(p,p).$ Much of the uncertainty in the level density arises from the determination of the fraction of levels that are not observed. The missing fraction of levels was determined by (a) the standard width analysis method that assumes a Porter-Thomas distribution for the reduced widths and (b) a recently developed method that analyzes the spacing distribution and assumes the Wigner distribution for the nearest-neighbor spacings. There are indications of parity dependence of the level densities for several of the spin-parity combinations.}, number={6}, journal={PHYSICAL REVIEW C}, author={Agvaanluvsan, U and Mitchell, GE and Shriner, JF and Pato, M}, year={2003}, month={Jun} }