SIMULTANEOUS HAND AND CLOTHING CHECKING FOR ALPHA AND BETA CONTAMINATION
A scintillation counter for the detection of alpha and beta particles simultaneously has been realized by the use of a dual phosphor screen for separating the two radiations. This principle has been used in the development of a monitoring instrument which checks the level of alpha and beta contumination of both hands simultaneously in five seconds, the whole operation being fully automatic and proof against misuse. Quantitative indication is given by meters, the final readings remaining until automatically reset when the instrument is used again. Visual and audible indication is given when the acceptable tolerance is exceeded. Alpha and betagamma probes are provided for checking clothing. These may be used simultaneously with the hand counters, so that three people may use the instrument at the same time. Circuits, photographs, and technical details of this instrument are given. A typical dual phosphor consists of silver activated zinc sulfide evenly deposited to a thickness of l2 mg/cm/sup 2/ and bonded to a block of plastic phosphor. The integral pulse amplitude distribution curve characteristic of the dual phosphor exhibits two distinct plateaux, one corresponding to alpha particles striking the zinc sulfide, and the other to beta particles passing into the plastic phosphor. It can be shown that two fixed thresholds, which depend on the relative response of the two phosphors to alpha and beta particles, exist, the amplitude level of discrimination for beta being lower than that for alpha. If two counting channels are arranged to trigger at different known amplitudes, the photomultiplier output pulses due to beta particles striking the plastic phosphor will cause one channel to trigger but not the other. Output pulses due to alpha particles producing light scintillations in the zinc sulfide will trigger both channels. The triggering of the beta channel by the alpha pulses will not appreciably affect the accuracy of the beta count since the tolerance for alpha radiations is very much less than that for beta radiation at acceptable hazard levels. Thus, by using this method of discrimination, it is possible to monitor alphi and beta contamination simultaneously. (auth)
- Research Organization:
- E.M.I. Electronics, Ltd., Hayes, Kent, Eng.
- NSA Number:
- NSA-13-006712
- OSTI ID:
- 4267541
- Report Number(s):
- A/CONF.15/P/294
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-59
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
BETA SCINTILLATION COUNTING WITH THIN PLASTIC PHOSPHORS
Method and circuit arrangement for discriminating between pulses generated by alpha and/or beta radiators
Related Subjects
ALPHA DETECTION
ALPHA PARTICLES
BETA DETECTION
BETA PARTICLES
BODY
CIRCUITS
CLOTHING
COATING
CONTAMINATION
CONTROL SYSTEMS
DISTRIBUTION
EFFICIENCY
ELECTRIC METERS
ERRORS
GAMMA DETECTION
MONITORING
OPERATION
PHOSPHORS
PHOTOMULTIPLIERS
PLANNING
POLYMERS
PULSE ANALYZERS
PULSES
RADIATION DOSES
SCINTILLATION COUNTERS
SCINTILLATIONS
SIGNALS
SILVER
SOUND
THICKNESS
TRACE AMOUNTS
TRIGGERS
USES
ZINC SULFIDES