Speaker
Description
A LaBr$_3$(Ce) scintillation detector is found to be the best among all other available scintillation detectors for timing spectroscopy work.
This has a very high light output and produces the best energy resolution ($\sim$ 4% at 662 keV). For a LaBr$_3$(Ce) detector, a glass
window PMT is found to be suitable and a much lower voltage is required compared to a BaF$_2$ detector. The timing performance of LaBr$_3$(Ce) is found
to be comparable to BaF$_2$. Prompt time resolutions of $\sim$ 300 and $\sim$ 210 ps have been obtained for a LaBr$_3$-BaF$_2$ detector combination
for 511 keV annihilation $\gamma$-rays of $^{22}$Na and 1173-1332 keV $\gamma$-rays of $^{60}$Co, respectively. Standard slow-fast coincidence assemblies using a four detector LaBr$_3$(Ce)-BaF$_2$ set up have been employed
for measurements of crystalline electric field gradient (EFG)
in intermetallic compounds (e.g. HfNi$_3$) by time differential perturbed angular correlation (TDPAC) spectroscopy. In this timing spectroscopy, angular correlation of a $\gamma$-$\gamma$ cascade
of the probe nucleus ($^{181}$Hf) is perturbed by the interaction of nuclear quadrupole moment of the probe nucleus with the EFG present
in the investigated material. Sensitivity of
this technique in determining weak EFG in a material depends on the time resolution of the coincidence set up. In the present report, we have
investigated EFG in binary alloy HfNi$_3$ by this technique. The excellent energy and time resolutions of LaBr$_3$(Ce)-BaF$_2$ detector set
up help to resolve five
electric quadrupole interactions in the investigated sample. The details of the measurement and the results obtained will be described.
| Presentation type | Oral |
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