Boron-Lined Proportional Counters0 pages

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S Detection of thermal neutrons in pulse

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mode

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S Watertight HN connector

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S High safety of use

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Sensitivity to thermal neutrons: Pulse mode 1 Background noise 2	4 <0.1	c.s"1/ n.cm"2.s"1 c.s-1
Neutron flux range: Pulse mode 3	0.3-3x105	n.cm"2.s"1
Exposure limits: Thermal neutrons Gamma exposure Gamma dose rate	max 1.7x1017 max 3.2x107 max 10	n.cm"2 Gy.h"1

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Insulating resistance at 800V 5:	min 1012	Q
Operating voltage: Nominal up to 200°C Maximum at 20°C Limit with no radiation	800 850 950	V V V
Charge collection time 6:	250	ns

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Detector: Materials: Cathode Central anode Insulator Brazing	High purity aluminium 025um stainless steel wire Al203 NiAu and AgCu
Sensitive layer: B enriched in 10B Mass	>92% 0.2	mg.cm"2
Filling gas (pressure)	Argon + 15% C02 (at 26.6 kPa)
Dimensions: Nominal diameter Detector length 8 Sensitive length	25.4 394 278	mm mm mm
Connector: Type Insulator	Al, female HN Watertight Al203

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This characteristic depends on the electronic equipment

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associated to the detector and the conditions of measurement.

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The figures have been determined with a Merlin-Gerin type SAITB

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equipment, working in current amplification (G = 80 dB) with a

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discrimination threshold of 600 mV.

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Characteristic depending on the electronic equipment associated

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to the counter.

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Value depending on the associated electronic equipment and the

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acceptable counting losses.

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Standard counting measurement conditions. Under radiation,

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gamma rays generate low amplitude pulses which are not counted

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due to the discrimination threshold. For dose rate more than 10

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Gy.h"1, pulse overlapping occurs which increases the counting rate

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without correlation with the neutron flux.

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The insulating resistance is measured between anode and

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cathode at 800 V, with polarity (+) on the anode. CAUTION: a

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wrong polarity could destroy the anode.

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Disappearing of C02 induces an increase of the charge collection

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time up to 2 us.

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The use of high purity aluminium further reduces the material

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activation after exposition to neutrons.

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On request this type of counter can be supplied with an integrated

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cable (CPNB24).

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Including temperature increase due to gamma radiation (effective

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above 10 gy.h"1). The leakage current in the connection cable

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increases rapidly with temperature. It is therefore necessary to

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take into account this characteristic, which limits the maximum

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temperature so that the ratio of wanted signal/parasitic signal

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remains acceptable. Consider CPNB24 detector if integral cable

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needed.

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1 Vibration test conditions : frequency 60 Hz , amplitude ± 1 mm.

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PHOTOIMIS

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25/02/2008

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