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The surrogate nuclear reaction method is being applied in many efforts to indirectly determine neutron-induced reaction cross sections on short-lived isotopes. This technique aims to extract accurate (n,γ) cross sections from measured decay properties of the compound nucleus of interest (created using a different reaction). The advantages and limitations of a method that identifies the γ-ray decay channel by detecting any high-energy ("statistical") γ ray emitted during the relaxation of the compound nucleus were investigated. Data collected using the STARS/LiBerACE silicon and germanium detector arrays were used to study the decay of excited gadolinium nuclei following inelastic proton scattering. In many cases, this method of identifying the γ-ray decay channel can simplify the experimental data collection and greatly improve the detection efficiency for γ-ray cascades. The results show sensitivity to angular-momentum differences between the surrogate reaction and the desired (n,γ) reaction similar to an analysis performed using low-lying discrete transitions even when ratios of cross sections are considered.

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Recent progress in the development of novel organic scintillators necessitates modern characterization capabilities. As the primary means of energy deposition by neutrons in these materials is n-p elastic scattering, knowledge of the proton light yield is paramount. This work establishes a new model-independent method to continuously measure proton light yield in organic scintillators over a broad energy range. Using a deuteron breakup neutron source at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and an array of organic scintillators, the proton light yield of EJ-301 and EJ-309, commercially available organic liquid scintillators from Eljen Technology, were measured via a double time-of-flight technique. The light yield was determined using a kinematically over-constrained system in the proton energy range of 1 − 20 MeV. The effect of pulse integration length on the magnitude and shape of the proton light yield relation was also explored. This work enables accurate simulation of the performance of advanced neutron detectors and supports the development of next-generation neutron imaging systems.

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From an experiment with Gammasphere and a 252 Cf spontaneous fission source, a new negative-parity band in 154 Nd and new negative-parity levels in 152 Nd were identified and the yrast bands were extended to 18 ϩ in 154 Nd and 20 ϩ in 152 Nd in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode. There is a constant difference as a function of spin between the J 1 values for the negative-parity band in 152 Nd and J 1 for the similar negative-parity band in 154 Nd, however, their J 2 values are essentially identical. These bands indicate a new kind of identical band. ͓S0556-2813͑98͒01004-8͔PACS number͑s͒: 23.20. Lv, 21.10.Re, 25.85.Ca, 27.70.ϩq The neutron-rich neodymium (Zϭ60) nuclei with Aу142 are situated at the important intersection of two transitional regions: the transition from spherical to prolate quadrupole deformation and the transition from octupole vibrational excitations to the static octupole deformation ͓1-6͔. So far little is known about octupole excitation states in the neutron-rich nuclei in contrast to the considerable data on quadrupole collectivity ͓5,7͔. Studies on octupole vibrational excitations in neodymium nuclei can provide tests of relevant nuclear models.Our previous studies ͓5,8͔ in neutron-rich nuclei in the Aϳ155 region revealed both identical moments of inertia ͑kinetic and dynamic͒ and identical gamma-ray energies in some cases. Therefore it is very interesting to identify possible sidebands in neodymium nuclei, looking for phenomena connected to identical bands as well as octupole deformation. In 144,146 Ba identical octupole bands associated with stable octupole deformation were observed ͓5,9͔.The new levels in 152,154 Nd were obtained from the analysis of ␥-ray spectra produced in the spontaneous fission of 252 Cf. A detailed description of the experimental procedures and analysis methods can be found in Ref. ͓5͔ and Ref. ͓10͔.The new transitions assigned to 154 Nd were identified by setting double gates on the known yrast transitions in 154 Nd from Ref. ͓5͔ and making sure that whenever a double gate was set on the new transitions, one not only observes the transitions corresponding to the partners ( 94,95,96 Sr) of 154 Nd with 4, 3, and 2 neutrons emitted, respectively, but also obtains the same yield ratios for their partners as obtained from double gating on the well known yrast transitions in 154 Nd. Figure 1 shows two partial coincidence spectra obtained by FIG. 1. ͑a͒ Coincidence spectrum obtained by double gating on the 162.8 and 895.0 keV transitions in 154 Nd. ͑b͒ Coincidence spectrum obtained by double gating on the 268.5 and 338.3 keV transitions in 154 Nd.

Relative 235 U(n,γ) and (n,f) cross sections from 235 U(d,pγ) and (d,pf) The internal surrogate ratio method allows for the determination of an unknown cross section, such as (n,γ), relative to a better-known cross section, such as (n,f), by measuring the relative exitchannel probabilities of a surrogate reaction that proceeds through the same compound nucleus. The validity of the internal surrogate ratio method is tested by comparing the relative gamma and fission exit-channel probabilities of a 236 U * compound nucleus, formed in the 235 U(d,p) reaction, to the known 235 U(n,γ) and (n,f) cross sections. A model-independent method for measuring the gamma-channel yield is presented and used.