Universität zu Köln

Regis, J. -M., Dannhoff, M., Jolie, J., Mueller-Gatermann, C. and Saed-Samii, N. (2016). On the time response of background obtained in gamma-ray spectroscopy experiments using LaBr3(Ce)detectors with different shielding. Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip., 811. S. 42 - 49. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1872-9576

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Abstract

Employing the gamma-gamma fast-timing technique with LaBr3(Ce) scintillator detectors allows the direct determination of lifetimes of nuclear excited states with a lower limit of about 5 ps. This limit is increased as soon as background is present in the coincidence spectra underneath the full-energy peaks of the gamma-gamma cascade. Our aim was to identify the components of the gamma-ray background by systematic gamma-gamma fast-timing measurements using different types of gamma shielding within a large gamma-ray spectrometer. The energy dependent physical zero-time response was measured using background-free full-energy peak events from the Eu-152 gamma-ray source. This is compared with the time response of the (Compton-) background distribution as obtained using the prompt Co-60 gamma-ray source. The time response of the typical Compton background is about 15 ps faster than the time response of background-free full-energy peak events. Below about 500 keV, a second type of background contributes by the detection of Compton-scattered gamma rays generated in the materials of the spectrometer around the detector. Due to the additional time-of-flight of the Compton-scattered gamma rays, this low-energy background is largely delayed. Compared with a bare cylindrical 1.5 in. x 1.5 in. LaBr3(Ce) detector, the BGO-shielded detector in the Compton-suppression mode improves the peak-to-total ratio by a factor of 1.66(5), while the Pb-shielded detector only slightly reduces the low-energy background. (C) 2015 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Regis, J. -M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dannhoff, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Jolie, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mueller-Gatermann, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Saed-Samii, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-284183
DOI:	10.1016/j.nima.2015.12.017
Journal or Publication Title:	Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip.
Volume:	811
Page Range:	S. 42 - 49
Date:	2016
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1872-9576
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language COMPTON SUPPRESSION SPECTROMETERS; LIFETIME MEASUREMENTS; EXCITED-STATES; DESPEC; FAIR Multiple languages Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28418