Improved electronics for 3He based neutron counters

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Improved electronics for 3He based neutron counters. / Boogers, Eric; Borella, Alessandro; Rossa, Riccardo.

In: EPJ Web of Conferences, Vol. 225, 05002, 01.01.2020, p. 1-4.

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@article{e17f0cfe60b44c359a25ad28ee08db60,
title = "Improved electronics for 3He based neutron counters",
abstract = "Several non-destructive assays techniques have been developed for the measurement of fissile materials in the fields of dismantling, decommissioning, nuclear security, and nuclear safeguards. Among these techniques, neutron coincidence counting is based on the detection of time-correlated neutrons from induced and spontaneous fissions. 3He Tubes have been the primary choice for neutron coincidence counting due to their high detection efficiency, rather low sensitivity to gamma-rays and proven field reliability. This paper covers the implementation of a new electronic setup to a Canberra WM3400 neutron coincidence counter. First we describe the properties of the used detectors, with focus on the characteristics of the default electronics and highlight its limitations such as the high input capacitance, short shaping time and the necessity for selected tubes. We then propose the new electronic setup to overcome these limitations. This setup includes a dedicated preamp for every tube , the possibility to adjust for gain differences between the tubes and a better optimised shaping time for 3He detectors. We carried out measurements with the two electronic systems to compare their performances in terms of gamma-ray sensitivity, efficiency and die-away time. The gamma ray sensitivity was measured with calibrated 137Cs and a 60Co sources at the Laboratory for Nuclear Calibration of the Belgian Nuclear Research Centre with dose rates between 10 £gSv/h and 50 mSv/h. Measurements with a 252Cf source were used to determine the die-away time of the system and the total measurement efficiency for the considered geometry. The measurements showed that, with the default electronics, neutron count-rates are already affected by gamma radiation at a dose rate of 10{"}i30 £gSv/h. On the other hand the neutron coincidence counter equipped with the new electronics proved to be insensitive to gamma-radiation up to a dose rate of at least 20 mSv/h. The high-voltage set with the new electronics is lower than in the case of the default electronics and is within the range recommended by the tubes manufacturer. The die-away time was not affected by the used electronics. A reduction of about 20{\%} in the neutron detection efficiency due to the used discriminator threshold was observed.",
keywords = "3He counters, Electronics, Neutron coincidence counting, Non destructive assay",
author = "Eric Boogers and Alessandro Borella and Riccardo Rossa",
note = "Score=10",
year = "2020",
month = "1",
day = "1",
doi = "10.1051/epjconf/202022505002",
language = "English",
volume = "225",
pages = "1--4",
journal = "EPJ Web of Conferences",
issn = "2100-014X",
publisher = "EDP Sciences",

}

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TY - JOUR

T1 - Improved electronics for 3He based neutron counters

AU - Boogers, Eric

AU - Borella, Alessandro

AU - Rossa, Riccardo

N1 - Score=10

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Several non-destructive assays techniques have been developed for the measurement of fissile materials in the fields of dismantling, decommissioning, nuclear security, and nuclear safeguards. Among these techniques, neutron coincidence counting is based on the detection of time-correlated neutrons from induced and spontaneous fissions. 3He Tubes have been the primary choice for neutron coincidence counting due to their high detection efficiency, rather low sensitivity to gamma-rays and proven field reliability. This paper covers the implementation of a new electronic setup to a Canberra WM3400 neutron coincidence counter. First we describe the properties of the used detectors, with focus on the characteristics of the default electronics and highlight its limitations such as the high input capacitance, short shaping time and the necessity for selected tubes. We then propose the new electronic setup to overcome these limitations. This setup includes a dedicated preamp for every tube , the possibility to adjust for gain differences between the tubes and a better optimised shaping time for 3He detectors. We carried out measurements with the two electronic systems to compare their performances in terms of gamma-ray sensitivity, efficiency and die-away time. The gamma ray sensitivity was measured with calibrated 137Cs and a 60Co sources at the Laboratory for Nuclear Calibration of the Belgian Nuclear Research Centre with dose rates between 10 £gSv/h and 50 mSv/h. Measurements with a 252Cf source were used to determine the die-away time of the system and the total measurement efficiency for the considered geometry. The measurements showed that, with the default electronics, neutron count-rates are already affected by gamma radiation at a dose rate of 10"i30 £gSv/h. On the other hand the neutron coincidence counter equipped with the new electronics proved to be insensitive to gamma-radiation up to a dose rate of at least 20 mSv/h. The high-voltage set with the new electronics is lower than in the case of the default electronics and is within the range recommended by the tubes manufacturer. The die-away time was not affected by the used electronics. A reduction of about 20% in the neutron detection efficiency due to the used discriminator threshold was observed.

AB - Several non-destructive assays techniques have been developed for the measurement of fissile materials in the fields of dismantling, decommissioning, nuclear security, and nuclear safeguards. Among these techniques, neutron coincidence counting is based on the detection of time-correlated neutrons from induced and spontaneous fissions. 3He Tubes have been the primary choice for neutron coincidence counting due to their high detection efficiency, rather low sensitivity to gamma-rays and proven field reliability. This paper covers the implementation of a new electronic setup to a Canberra WM3400 neutron coincidence counter. First we describe the properties of the used detectors, with focus on the characteristics of the default electronics and highlight its limitations such as the high input capacitance, short shaping time and the necessity for selected tubes. We then propose the new electronic setup to overcome these limitations. This setup includes a dedicated preamp for every tube , the possibility to adjust for gain differences between the tubes and a better optimised shaping time for 3He detectors. We carried out measurements with the two electronic systems to compare their performances in terms of gamma-ray sensitivity, efficiency and die-away time. The gamma ray sensitivity was measured with calibrated 137Cs and a 60Co sources at the Laboratory for Nuclear Calibration of the Belgian Nuclear Research Centre with dose rates between 10 £gSv/h and 50 mSv/h. Measurements with a 252Cf source were used to determine the die-away time of the system and the total measurement efficiency for the considered geometry. The measurements showed that, with the default electronics, neutron count-rates are already affected by gamma radiation at a dose rate of 10"i30 £gSv/h. On the other hand the neutron coincidence counter equipped with the new electronics proved to be insensitive to gamma-radiation up to a dose rate of at least 20 mSv/h. The high-voltage set with the new electronics is lower than in the case of the default electronics and is within the range recommended by the tubes manufacturer. The die-away time was not affected by the used electronics. A reduction of about 20% in the neutron detection efficiency due to the used discriminator threshold was observed.

KW - 3He counters

KW - Electronics

KW - Neutron coincidence counting

KW - Non destructive assay

UR - https://ecm.sckcen.be/OTCS/llisapi.dll/open/37730685

U2 - 10.1051/epjconf/202022505002

DO - 10.1051/epjconf/202022505002

M3 - Article

VL - 225

SP - 1

EP - 4

JO - EPJ Web of Conferences

JF - EPJ Web of Conferences

SN - 2100-014X

M1 - 05002

ER -

ID: 6758235