Spark Counter Research Articles

The Suppression of Destructive Sparks in Parallel Plate Proportional Counters

We find that high energy background events produce localised sparks in parallel plate counters when operated in the proportional mode. These sparks increase dead-time and lead to degradation ranging from electrode damage to spurious pulsing and continuous breakdown. The problem is particularly serious in low energy photon detectors for X-ray astronomy which are required to have lifetimes of several years in the high radiation environment of space. For the parallel plate imaging detector developed for the European X-ray Observatory Satellite (EXOSAT) we investigate quantitatively the spark thresholds, spark rates and degradation processes. We discuss the spark mechanism, pointing out differences from the situation in spark chambers and counters. We show that the time profile of the sparks allows us to devise a spark suppression system which reduces the degradation rate by a factor of ~200.

Experience with a Track Etch Detector in Personnel and Environmental Dosimetry

Abstract A neutron dosimetry system with a fission track detector and a spark counter has been used for more than 10 years in routine personnel and environmental dosimetry. For personnel dosimetry the badge consists of a 235U and a 232Th converter and a Makrofol KG detector. This badge is used at SIN (600 MeV proton accelerator) and for source handling (Am-Be) for a total of about 700 radiation workers. For environmental dosimetry (skyshine measurements around SIN and GSI Darmstadt) a 235U converter and a Makrofol KG detector are placed in the centre of a moderating sphere. For both systems data on sensitivity, energy dependence, reproducibility and fading, as well as a discussion of the long term experience and actual problems, are given.

Energy-Dependent Neutron Detection Sensitivity of Cellulose Nitrate Track Detector

A cellulose nitrate track detector, LR-115 (Type II), was studied experimentally to observe its neutron energy response when a radiator, such as fissionable material, is absent. The detector was exposed to monochromatic neutrons from the D (d, n) He reaction produced by a Van de Graaf accelerator. Through-etched and almost through-etched tracks in the detector were counted by two different methods: 1) optical microscope counting with an automatic image analyzing system and 2) spark counting. The detection sensitivity was obtained in the neutron energy region lower than 5 MeV and it was found that only α-particles from (n, α) reactions could be detected in both counting methods. We derived the counting probability of α-tracks induced in the detector and the threshold energies for neutron detection.

A test of planar spark counters at the PEP storage ring

A test of planar spark counters (PSCs) at the PEP electron-positron storage ring showed the following. PSCs can be used under harsh experimental conditions without long term degradation of resolution. On-line time-of-flight resolution were below 200 ps, coordinate resolutions better than 4 mm, both limited to these values by the resistivity of the semiconducting glass and the electronics used. The best single counter time resolution under realistic conditions at the storage ring was 76 ps. Pulse height was a good indicator of the number of particles striking a counter. Subsequent measurements using cosmic rays gave a single counter time resolution of 50 ps.

Limitations in Application of Spark Counter in Counting of Fission Fragments at Various Angles of Incidence and That of Their Energy Degradation in Air

Limitations in Application of Spark Counter in Counting of Fission Fragments at Various Angles of Incidence and That of Their Energy Degradation in Air

Limitations in application of spark counter in counting of fission fragments at various angles of incidence and that of their energy degradation in air.

Reports had been made of a spark counter and this has now been used in the studies of detection and counting of fission fragments, incident on an SSNTD at various angles of incidence, from a 252Cf source. The effect of their straggling in air has also been observed with the use of this counter in the determination of the number of fission fragments. The implications of these studies may be useful in the measurements of total fission events occurring from a nuclear reaction of a heavy element which is of some interest to the reactor and applied nuclear physicists.

Spark counting of solid state nuclear tracks Part 1: Effect on counting response linearity of electrode size and shunt capacitance

The dominant parameter for maintaining response linearity (i.e. < 5% non-linearity) of counted tracks vs chemically etched tracks in 10 μm thick MAKROFOL KG polycarbonate film is shown to be the size of the spark electrode. This was found to be true for electrodes with rounded upper edges having diameters within the range of at least 38 to 12 mm. At a plateau-optimized sparking potential of 520V, linearity was maintained up to a track density of 300 counts cm -2 using a spark electrode of 38 mm diameter. The optimum spark electrode diameter was found to lie around 16 mm, linearity being maintained up to ∼ 1100 counts cm -2. Throughout this study a polyester film aluminized on both sides to a total aluminum thickness of 0.037 μm (± 10%) was used as the conductor between the spark and the return electrodes.

Neutron sensitivity of SSNTD

Various types of solid state nuclear track detectors (SSNTDs) with and without converter radiators were irradiated with neutrons of different energy spectra in order to obtain information on their neutron sensitivity in beam dosimetry. Track revealing was performed by chemical etching. A manual track counting technique was chosen except for the case of thin plastic foils, where also automatic spark counting was used.

The jumping spark counter and its development as an aid to measuring alpha activity in biological and environmental samples

The jumping spark counter is a cheap and robust instrument for the counting of alpha particle activity, over several square centimetres of a solid state nuclear track detector (SSNTD). A description of a spark counter suitable for use with thin SSNTDs is given, together with its mode of operation and a brief history of its development. Its use in the measurement of alpha-particle activity from both thick pellet-sources and thin electrodeposited alpha-particle sources is described. The latter sources, when produced by suitable chemical separations, are both specific and extremely sensitive; and levels of 10 -14 Ci or less of plutonium may be measured on such sources.

A new approach to measuring fission cross-section ratios

Abstract Fission cross-section ratios of 238U/235U, 238U/237Np, 235U/237Np and 239Pu/235U were determined in the range of 13.5–14.8 MeV neutron energy. Neutrons were produced by a 180 kV Cockcroft-Walton generator using the T(d,n)4 He reaction. The fission events from samples were detected with 12 μm Makrofol KG polycarbonate foils. A 2π geometry was used. The etched foils were evaluated by a jumping spark counter (JSC). The trends of the relative cross sections within the limits of errors are in good agreement with those deduced from various compilations.

Diameter measurement of through-etched particle tracks by means of a spark counter

The application of spark counting for the diameter measurement of through-etched particle tracks is described. Information about the diameter distribution can be obtained by determining the number of sparks as a function of the sparking voltage. An empirical expression to calculate the sparking voltage as a function of foil thickness and track diameter is presented. The method was tested for a thickness range of 5–14 μm, and may be used in a diameter range of 0.1–1 μm.

A new application of the spark counter: Pore size measurement of nuclear track microfilters

Based on the known spark counting technique a method for pore size measurement in nuclear track microfilters is presented. The increased electric strength of a fine pore in a dielectric material is utilized to establish this new method, in which the sparks are counted as a function of the growing sparking voltage. Both electrodes are made from aluminized polyester foil in order to reduce the effect of multiple sparking in the applied voltage range of 600–1800 V corresponding to a pore diameter range of 1.5-0.1 μm. Due to the high pore density of NTMFs it is necessary to add a reduction foil of a low hole density to select some small areas in the NTMF for sparking. In this way the method can be applied to pore size measurement in the porosity range used in separation processes.

A modified automatic spark counting system for uranium exploration

A modified design of a jumping spark counter capable of counting the damage trails produced by alpha particles emitted in the decay of radon (released from uranium ore bodies) has been developed. The device consists of two electrodes made up of aluminised mylar and thin metallic foil respectively. The modified system is convenient and yields better plateau than that obtained by using the conventional systems. Efforts have been made in optimising the device for attaining one to one correspondence between the microscopically observed hole density and the track counts in the system. Experience shows that the counting system can be effectively used for the evaluation of uranium ore samples.

A new method for electrochemical etching: I. Results with dc voltage

ABSTRACT A new method of electrochemical etching using dc voltage is described, where the etched-through tracks in the plastic foil are non-shorting. These non-shorting characteristics of perforating tracks are reminiscent of the self-healing properties of holes-induced discharges in the spark counter.

Nuclear track detection by avalanche-type processes: Electrochemical etching, spark and breakdown counter

ABSTRACT The spark counter and the electrochemical etching greatly facilitate the counting of damage tracks in insulators. The normal electrochemical etching presents various shortcomings, which can be eliminated by a newly discovered electrochemical etching. The damage track detectors are only capable of storing the information. By contrast, the thin film breakdown counters provide real-time detection. The trait common to all the registration techniques described in this paper is the use of avalanche-type of processes (typically non-shorting electrical breakdown) to simplify the track counting and visualization.

Application of solid state nuclear track detector in neutron dosimetry

ABSTRACT This paper describes a series of works which have been done in our laboratory in the past years with Solid State Nuclear Track Detector for neutron dosimetry. The main results of our works are briefly included as follows: 1. Determination of the basic characteristics of fission track detector, a formula for calculating the efficiency of neutron detection is presented; 2. Neutron spectrum measurement with SSNTD; 3. A personnel neutron dosimeter and spark counting; 4. Basic properties of fast-neutron-induced recoil tracks in polycarbonate foils.

Development of thin CR 39 detector films for spark counting of recoil proton tracks

Abstract The excellent properties of CR39 as a fast neutron detector are well known. The aim of this work was to develop a compound detector system which combines the advantages of CR39 with the fast read-out of spark counting. Usually the detector films are read by optical equipment, which is very slow. A composite film consisting of a CR39 film of 35 μm thickness and a polyester sheet of about 150 μm thickness has been manufactured which is resistant to the NaOH etchant. The effective evaluation technique of electrochemical etching (ECE) was applied.

Application of solid state nuclear track detectors for measuring fission cross-section ratios

ABSTRACT Fission cross-section ratios of 238U/235U, 238U/237Np, 235U/237Np and 239Pu/ 235U were determined in the range of 13.5–14.8 MeV neutron energy. Neutrons were produced by a 180 kV Cockroft-Walton generator using the T(d,n)4 He reaction. The fission events from samples were detected with 12 μm Makrofol KG polycarbonate foils. A 2π geometry was used. The etched foils were evaluated by a Jumping Spark Counter (JSC). The trends of the relative cross sections within the limits of errors are in good agreement with those deduced from various compilations.

The application of solid state nuclear track detectors in nuclear safeguards

ABSTRACT The application of solid state nuclear track detectors (SSTD) for the determination of the burn-up of spent reactor fuel elements has been investigated. The results of the SSTD's were compared with two active methods such as fuel element scanning with a fission chamber and a ionization chamber. In addition the gamma profile was measured with thermoluminescence dosimeters. The SSTD using Makrofol KG were exposed as a sandwich with a 93% enriched uranium foil to detect spontaneous neutrons emitted from transuranic elements. Through a (n, f)-reaction the neutron density was evaluation by counting the fission tracks with a jumping spark counter. Two TRIGA research reactor fuel elements, one with low the other one with high burn-up were investigated by this method and the SSTD results were almost conform to the other three methods mentioned above. Finally, this method has been slightly modified to be applicable also for power reactor fuel.

Spark Counting of Tracks Directly Induced by Fast Neutrons in Cellulose Nitrate Detector

Studies are described on spark counting of tracks directly induced by fast neutrons in the cellulose nitrate detector, LR-115 (Type H). The spark counting for the detector irradiated by neutrons from an Am-Be source was performed under different etching conditions and different sample setting in the spark counter used in the experiment. The characteristic curves of spark counts vs. neutron fluence was determined, and sensitivity of the detector treated by the method was obtained to be 3 × 107 for the fluence between 1 × 107 and 2×109 n/cm2 in the most adequate condition. The reproducibility of this method was estimated to be 13%.