LB 134
7. Probes for the LB 134
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7. Probes for the LB 134
7.1 Internal Dose rate Probe
The integrated gamma dose rate probe is a Geiger-Müller coun-
ter tube and is suitable for the low dose rate range from 0.1
µSv/h to 20 mSv/h and for an energy range from 50 to 1300
keV. Calibration factor: 0.627 µSv/h/cps, intrinsic background:
0.07 cps. The probe is calibrated to the H*(10) standard (ambi-
ent equivalent dose rate). To extend the life of the batter-
ies/rechargeable batteries, the power supply of the internal
probe is switched off in the menu when the probe is not in use.
7.2 Scintillator Probes with ZnS for Contamination Measurements
In this chapter we will describe the Berthold scintillation probes
designed for the measurement of alpha, beta and gamma con-
tamination in detail.
The principle of operation of scintillation counters
In conventional scintillation counters, the radiation to be meas-
ured hits one or several scintillator layers. The resulting light
flashes are passed on directly, or bundled by a suitable reflec-
tor, to the photomultiplier.
The current state of the art
Up to now, sandwich detectors consisting of two layers were
used to measure alpha, beta and gamma radiation: ZnS for the
alpha radiation and plastic scintillators for beta and gamma ra-
diation, with the ZnS layer facing the sample.
The disadvantages of this method are the low sensitivity for
low-energy beta radiation, which must penetrate the ZnS layer,
and a poor discrimination between types of radiation (strong
spillover effects in the beta channel), and high manufacturing
costs. Moreover, with smaller beta energies, such as C-14,
these detectors show a higher position dependence through the
detector surface.
New measurement method by B
ERTHOLD
T
ECHNOLOGIES
Contamination detectors with ZnS scintillators use a single scin-
tillator made of zinc sulfide (ZnS) to measure the radioactivity.
The radiation to be measured strikes the scintillator. The result-
ing flashes of light are conducted by a suitable reflector to a
photomultiplier with a suitable preamplifier and discriminator
stage and measured.
Summary of Contents for LB 134
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Page 6: ...LB 134 Content IV...
Page 8: ...LB 134 Working with the User s Manual VI...
Page 10: ...LB 134 Safety Instructions VIII...
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