S. D. Hoblit

Low-energy photon scattering off 142,146,148,150Nd: An investigation in the mass region of a nuclear shape transition☆

Abstract Nuclear resonance fluorescence experiments have been performed on the nuclei 142,146,148,150 Nd, which are located in the mass region of a nuclear shape transition from a spherical ( 142 Nd) to a well-deformed shape ( 150 Nd). Bremsstrahlung of 4.1 MeV endpoint energy served as the photon source. The scattered photons were detected by high-resolution Ge-spectrometers. Precise excitation energies, decay branching ratios, and ground-state decay widths of numerous new spin-1 states have been extracted.

First Extraction of a Spin Polarizability of the Proton

A proton spin polarizability characterizing backward Compton scattering has been extracted from a dispersion analysis of data between 33 and 309MeV. This backward spin polarizability, {delta}{sub {pi}}=[27.1{plus_minus}2.2(stat +syst){sup +2.8}{sub {minus}2.4}(model )]{times}10{sup {minus}4} fm {sup 4} , differs significantly from theoretical estimates and suggests a new contribution from the nonperturbative spin structure of the proton. This {delta}{sub {pi}} value removes an apparent inconsistency in the difference of charge polarizabilities extracted from data above {pi} threshold. Our global result, {ovr {alpha}}{minus}{ovr {beta}}=[10.11{plus_minus}1 .74(stat+syst){sup +1.22}{sub {minus}0.86}(model)]{times}10{sup {minus}4} fm{sup 3} , agrees with the previous world average of data below 155MeV. Our value for {ovr {alpha}}+{ovr {beta}}=[13.23{plus_minus}0 .86(stat+syst){sup +0.20}{sub {minus}0.49}(model)]{times}10{sup {minus}4} fm{sup 3} is consistent with a recent reevaluation of the Baldin sum rule. {copyright} {ital 1998} {ital The American Physical Society}

Parity assignments in nuclear resonance fluorescence experiments using compton polarimeters

Abstract Measurements of the linear polarization of resonantly scattered photons have been used for model-independent parity determinations in nuclear resonance fluorescence experiments. Two different Compton polarimeters, a five Ge detector arrangement and a sectored Ge(Li) detector, have been installed at the bremsstrahlung facility of the Stuttgart Dynamitron Accelerator. The following spin and parity assignments have been achieved to excited states (excitation energy E x ): 142 Nd: E x = 3.425 MeV, J π = 1 − ; 150 Nd: E x = 2.894 MeV, J π = 1 + ; E x = 2.994 MeV, J π = 1 + ; E x = 3.058 MeV, J π = 1 + ; 232 Th: E x = 2.043 MeV, J π = 1 + .