Radiant energy – Invisible radiant energy responsive electric signalling – Including a radiant energy responsive gas discharge device
Patent
1982-08-09
1985-09-24
Smith, Alfred E.
Radiant energy
Invisible radiant energy responsive electric signalling
Including a radiant energy responsive gas discharge device
H01J 4706
Patent
active
045434832
DESCRIPTION:
BRIEF SUMMARY
This application corresponds to German patent DE No. 31 00 447 C2, issued Feb. 24, 1983.
The invention relates to a radiation measuring instrument for detecting ionizing radiation.
The novel instrument should have high sensitivity to beta, gamma, X and neutron radiation, for instance, so that it will be suitable as a contamination measuring instrument for traces of weakly radioactive contamination. Its simple, sturdy and compact construction should suit it for use as a universal radiation warning device. It should be possible to manufacture and adjust the instrument according to the invention with high accuracy, and to produce it simply and inexpensively.
BACKGROUND
Pocket-sized counter tube instruments for detecting radioactivity are known. However, the miniature Geiger counters presently available are not very sensitive and are therefore not suited to the detection of slightly radioactive contamination in the environment. Specialized contamination monitors are generally used for that purpose, being equipped with special, highly sensitive counter tubes. The construction of such instruments, however, is so expensive that there could be no question of their use except by professionals because of the high cost involved. The basic situation thus described above in general will now be discussed in greater detail.
Some of the requirements to be made of a reliable radiation measuring instrument are set forth in the DIN 6818 and DIN 44 801 standards. It must furthermore be noted that a hand instrument for measuring contamination in the lowdose range must have a certain minimum sensitivity, so that a brief and/or slight increase in the counting rate above the average background level occurring in the course of a scanning movement can also in fact be recognized by the user of the device.
In practice, the only suitable contamination measuring devices have been those which respond to the natural background level of approximately 10 microrem per hour with a counting rate of 1 s.sup.-1 or more. At low counting rates, it is extremely difficult to detect variations in the counting rate directly, regardless of the manner in which the counting rate is registered or displayed. When this is done using an indicator instrument, then even when the maximum permissible time constant of 4 s (DIN 44 801) is used, the reading accuracy at low counting rates is insufficient. Optical or acoustical single-pulse registration produces no better results, because the human organism is not capable of perceiving with sufficient accuracy stochastic events which elapse slowly.
From the above discussion it will be understood that the low-voltage counter tubes having a noble-gas/halogen atmosphere presently available and of standard design, and in particular the miniature versions, cannot be considered appropriate for the construction of an efficient radiation measuring device suitable for measuring contamination, because the sensitivity of such standard detectors is insufficient for reliably detecting weak radiation.
In recognition of this fact, the use of proportional counter tubes of large surface area was advocated at quite an early date. Proportional counter tubes are known which have been optimized, at relatively great expense, in the direction of maximum possible sensitivity and which are designed as measuring instruments for alpha and beta radiation, being particularly in the form of liquid flow counters having thin-walled windows. Window-type counter tubes of this kind must, because of their construction, all be operated with a constant high voltage of several kilovolts, and therein lies one of the primary difficulties in the miniaturization of highly sensitive radiation measuring instruments.
Portable embodiments having a built-in, large-surface proportional counter tube are also known, which are commercially available as workplace monitors in order to satisfy the requirements of Article 64 of the Radiation Protection Regulations of the Federal Republic of Germany. Given the considerable expense of these instruments, their structural
REFERENCES:
patent: 2679609 (1954-05-01), Meloy
patent: 2736817 (1956-02-01), Bell, Jr.
patent: 2974248 (1961-03-01), Auxier et al.
patent: 3174042 (1965-03-01), White
patent: 3372295 (1968-03-01), Sparks
patent: 3614442 (1971-10-01), Brodsky
patent: 4178509 (1979-12-01), More et al.
patent: 4191886 (1980-03-01), Basso et al.
Korff, "Electron and Nuclear Counters: Theory and Use" Van Nostrand Co., N.Y., 1955, pp. 206-209.
Zaubitzer, "Feinwerktechnik", 8, 1957, pp. 276-277.
"Mini Monitor", Trade brochure, undated.
Fields Carolyn E.
Smith Alfred E.
LandOfFree
Radiation measuring instrument does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiation measuring instrument, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation measuring instrument will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1615745