Gas-discharge Counters Research Articles

An instance of a temporary increase in the intensity of heavy nuclei during the flight of the third satellite

To determine the cosmic ray nuclear component, a cerenkov integral-type counter was installed on the third artificial earth satellite similar to the counters used on cosmic rockets(1-3). This counter detected nuclei with 2 2. 5,Z z 12-14,Z ;3 31-34 and 2 > 34. In order to investigate the chemical composition of the nuclear component, brenkov differential-type counters@) were also installed. Each differential-type counter was associated with two groups of gas-discharge counters which formed a telescope with the geometric factor l? w 2.5 . lo4 cm2ster. The total energy of the detected nuclei exceeded 1+1*5 BeV. In this paper a description is given of a short increase in the intensity of the heavy nuclei, similar to that detected during the flight of the second cosmic rocket(*). To observe variations in the intensity of the nuclear component, the most favourable conditions occur in free space outside Earth’s magnetic field. Near Earth, owing to geomagnetic effects, the intensity varies widely in flight from the equator to high latitudes (the latitude effect>: Such variation hinders observation of temporary variations. Yet the intensity at a particular instant can be compared with the mean intensity on the corresponding geomagnetic latitude. High latitudes are the most convenient for which the mean intensity of the nuclear component should be independent of latitude. There are two reasons for the constancy of the mean intensity at high latitudes. Firstly, owing to the existence of a region of “highlatitude clipping” where the intensity is constant, low-energy nuclei do not enter into orbit round Earth. Secondly, owing to the energy threshold of Cerenkov counters, nuclei with total energy less than 1+1*5 BeV/nucleon are not recorded and this too must lead to constancy of the mean intensity at high latitudes. Figures 2 and 3 in another paper of this journal w show the dependence of nuclei with Z 2 2, Z 2 5 and Z 2 12-14 on latitude, as found during the flight of the third cosmic rocket. It is apparent from these diagrams that, beginning from latitudes 50-55*, intensity remains unchanged within the limits of statistical error. If the intensity of the nuclei increases notably for a short period of time during flight above this region, such an increase is to be regarded as a variation in the intensity of the nuclear component, provided of course that the increase is large enough and that it cannot be due to statistical fluctuations. While scrutinising the material obtained during the flight of the third satellite, just such an increase was noted as at 1 I.20 hr world time 1 December 1960 for 12 min. At this time the satellite was in the high latitude region. According to the integral-type counter, the intensity of nuclei with 2 > 12-14 increased by a factor of 2-8 f l-4 compared with the mean value for geomagnetic latitudes 50-70*. The increase in intensity for nuclei with z 2 5, as well as for 2 > 2 (according to the differential counter), was within the limits of statistical error throughout the period. In the shorter period from 11.20 to 11.26 hr, the

DOSIMETRIC MEASUREMENTS ON THE SECOND SOVIET SPACESHIP SATELLITE

Readings of counters placed inside Sputnik II are given for one portion of its trajectory. The readings were taken by a gas-discharge counter STS-5 and a NaI crystal scintillator counter that registered gamma quanta, charged particles with a 25-kev counting threshold, and the aggregate energy liberation of ionizing radiations in the crystal. (C.E.S.)

The outer radiation belt of the earth at the altitude of 320 km

Scintillation and gas-discharge counters on the second Soviet spaceship allowed a detailed investigation of the outer radiation belt near the earth and established its boundaries in relation to longitude. The spaceship orbit was almost circular at an altitude of 306 to 339 km. The energy threshold of the counter channel was 25 kev. (W,D.M.)

Investigation of charged particle intensity during the flights of the second and third space-ships

During the flight of the second and third earth satellites records of the charged particle flux at altitudes from 187 to 339 km and latitudes from -65 to +65 deg were obtained. A counter telescope, which consisted of two sets of gas discharge counters, was used as the recording instrument. The resolving time of the double coincidence circuit was 2 x 10/sup -5/ sec. (W.D.M.)

Methods of directional detection of gamma radiation

An analysis is given of the principal characteristics and parameters of directional radiation detectors. Particular attention is paid to directional scintillation counters of the compensated type, and it is shown that they possess much better parameters than analogous instruments using gasdischarge counters. A description is given of various compensating systems which may be useful in connection with the detection and measurement of radioactive elements.

Methods of directional recording for gamma rays

The basic characteristics and parameters of a directional radiation receiver are analyzed. Scintillation radiometers of the directional compensation type are studied and their advantages over similar gas discharge counters are stressed. Descriptions are given of various compensation systems for detecting and measuring radioactive elements. (tr-auth)

Radiation Measurements During the Flight of the Second Cosmic Rocket

T INSTRUMENTATION for measurement of radiation aboard the second Soviet cosmic rocket launched to the moon on Sept. 12, 1959 was installed with the objective of obtaining new data on the outer radiation belt of Earth, recording the radiation of cosmic rays along the path from Earth to the moon, and searching for a possible radiation belt of the moon. The number of instruments and the measurement scope were increased in comparison to the first cosmic rocket (l). In addition, some of the radiation recording instruments were mounted outside the hermetically sealed container (at a distance of 56 cm from its surface), which considerably reduced the shielding of these instruments by other apparatus. The entire instrumentation consisted of six gas discharge counters and three scintillation detectors. Mounted inside the container were the following instruments : 1 Scintillation counter A (a detector consisting of a cylindrical crystal of sodium iodide, having a diameter of 39.5 mm and a height of 40 mm). This instrument recorded the entire ionization produced by the ionizing radiation in the crystal and the counting rate corresponding to the different energy outputs in the crystal: Over 60 kev (threshold I); over 600 kev (threshold II) and over 3.5 mev (threshold in). 2 Gas discharge counter No. 4, having a diameter of 1 cm and a length of 5 cm, surrounded by a supplementary copper shield 1.5-mm thick. 3 Gas discharge counter No. 5, having a diameter of 1 cm and a length of 5 cm, surrounded by supplementary shields of lead 3-mm thick and of aluminum 1-mm thick. These three instruments were covered by a 1-gm per cm thick aluminum envelope. Also, approximately 20% of the entire solid angle was covered with material with a thickness of 10 gm per cm. Mounted outside the container were the following instruments : 4 Scintillation counter B (a detector consisting of a cylindrical crystal of sodium iodide having a diameter of 39 mm and a height of 40 mm). This instrument recorded the entire ionization produced in the crystal; the rate of impulse counting corresponded to the different energy levels in the crystal: Over 45 kev (threshold I) and over 450 kev (threshold II). The crystal of this counter was shielded with a layer of aluminum 1-gm per cm thick, and only 5% of the entire solid angle was covered with a larger amount of material (up to 10 gm per cm). 5 Scintillation counter V (a detector consisting of a crystal of cesium iodide 3-mm thick, having a diameter of 30 mm, covered on the side of the open space with an aluminum coating 1.2-mg per cm thick). This instrument recorded the total ionization produced in the crystal. 6 Gas discharge counter No. 1, encased in a lead shield

On the efficiency of gas-discharge counters

On the efficiency of gas-discharge counters

Investigations of the performance of gas-discharge counters with a controlled pulsed power supply

With a pulsed power supply for gas-discharge counters, counting errors, determined by the dead time, are eliminated. Because of this, the possibility arises of using hodoscope systems of counters with a controlled pulsed power supply in experiments carried out with accelerators having a large background of extraneous radiation. In the present work the counting characteristics were investigated, and also measurements were carried out of the efficiency and the resolving power of self-quenching factory-produced counters with a controlled pulsed power supply. It is found that in the case of short-duration pulses (pulse length ∼ 10−6 sec) the counters can work under over-voltages of up to 2 kv. At the same time there is no necessity to amplify the pulses in the hodoscope channel or to use a discriminator to obtain their coincidences with the control pulse. Each channel, in this case, in addition to the counter contains a load resistance and a neon lamp. The considerable simplification of the system, by comparison with the usual type of hodoscope, and also the reliable performance of counters with pulsed power supplies, make such systems also useful for the study of cosmic radiation.

A Microwave Gas Discharge Counter for the Detection of Ionizing Radiation

Characteristics of a gamma-ray counter making use of a 3000-megacycle gas discharge in a coaxial mode cavity resonator are described. The breakdown of a discharge in gases at these frequencies does not depend upon secondary effects. Since the breakdown is not controlled by positive ions, shorter breakdown and resolving times than those of a Geiger-Müller counter are realized. In the high frequency discharge, ambipolar diffusion is the controlling factor in loss of electrons. A d.c. clearing field is superimposed on the a.c. field to eliminate electrons rapidly. A quenching agent is present to suppress electron emission from positive ion bombardment of the walls. The discharge is extinguished by reducing the magnetron power electronically. The plateau and sensitivity characteristics are similar to those of a Geiger-Müller counter.