Sensitivity Of CR-39 Research Articles

Can Electric Field Influence the Sensitivity of CR-39 Detector?

Studies have been carried out to investigate the effect of electric field on the sensitivity of CR-39. Samples of CR-39 were exposed to neutrons and α particles under different electric field values and etched. From the measured track densities and diameters, CR-39 sensitivity and etching rates were determined. It was found that the application of voltage increases etching rates, but the sensitivity of CR-39 remains unchanged.

The effect of heating and freezing in water on the characteristics of CR-39 and CN-85 plastic detectors

The annealing dependence of the mean track diameter, track density and sensitivity of CR-39 and CN-85 plastic detectors was studied. The annealing process was carried out in water at 100°C and 0°C for CR-39, and at 80°C and 0°C for CN-85. α-Particles of different energies were used to irradiate the samples. The measurements were carried out on samples, annealing before and after irradiation. It was found that the annealing process, after irradiation, increases the relative track density up to 2·6 and 1·8 for CR-39 and CN-85, respectively. It was also observed that the mean track diameters of α-particles increased on annealing for both detectors, the increases ranging between 17 and 25% of the unannealed values. Finally, the sensitivity of CR-39 was found to be greatly reduced when annealed in boiling water.

Effects of pre-soaking on characteristics of CR-39

Abstract Pre-soaking is a process during which an exposed track detector is soaked in a liquid chemicals for a few hours just before etching. Studies have been made to determine the effects of pre-soaking on the characteristics of CR-39 by using various soaking chemicals. The gradual hydrolysis of CR-39 is promoted by the pre-soaking in hot water and improved in sensitivity of CR-39. The beneficial effects of pre-soaking in hexachloro butadiene or dioctylphthalate on the improvement of etched-surface quality of CR-39 were confirmed.

CR-39 detector and experimental techniques of cosmic supermassive particles search

The characteristics of CR-39 plastic for cosmic supermassive particles search are described. The long-term effects of temperature, oxygen, and water vapor on the sensitivity of CR-39 and the pre-soaking effect were investigated. For processing the large number of CR-39 plates, a way of mass etching was also investigated and a large etching system was developed. In addition, the procedure of the experiment searching for cosmic supermassive particles is presented.

ＣＲ‐３９プラスチックの焼鈍による感度の向上

ＣＲ‐３９プラスチックの焼鈍による感度の向上

CR-39 and detection of very high-energy neutrons

A controlled experiment was done to study the response as well as the detection efficiency of CR-39 (DOP) detectors to very high energy neutrons originating from 9 Be (α, xn ) reaction at E α approx. 50 MeV from the Variable Energy Cyclotron at Calcutta. A NE213 liquid scintillation neutron detector coupled to a photomultiplier having neutron-gamma pulse shape discrimination property was used to record the neutron flux as well as the spectrum. The CR-39 results obtained are compared with the NE213 monitor data. The sensitivity of CR-39 for neutron detection comes out to be 5 tracks cm -2 mrem -1 for the high energy neutrons used.

A novel “rapid development” plastic track detector

In an attempt to improve on the sensitivity of CR-39 a novel polymeric material has been developed which, although not yet optimised, shows an alpha response comparable to that of CR-39. The material is an alternating copolymer made by UV initiated bulk copolymerisation of diethylene glycol bis (allylcarbonate) with liquid sulphur dioxide. The polymer network incorporates - SO 2 - links into polyallyl chains of CR-39 and thus makes them radiation sensitive and susceptible to etching. The bulk material can be etched in NaOH (aq) and can be used as a rapid development film with an α-track etching time of about 1 minute. By etching in Na 2 CO 3 (aq) the SO 2 links only are attacked and etching gives an alpha response comparable to CR-39. The polymer has a ceiling temperature above which it becomes thermodynamically favourable to depolymerize back into monomers. It becomes kinetically possible for this to happen upon irradiation and hence this gives a mechanism by which V T can be increased. It has been found that V T (10)/V B -1 is enhanced by etching at temperatures above 75°C by a factor of ∼3.

A study of the molecular structure in CR-39

Abstract A technique is presented for examining the molecular structure of CR-39 by analysis of the etch products from hydrolysis of the polymer network. The CR-39 network consists of polyallyl chains joined by diethyleneglycol dicarbonate links. The etching cuts the carbonate links and liberates the polyallyl chains which makes them amenable to common analytical methods. Gel Permeation Chromatography was used to characterize the chain lengths and their distribution. It was found that the average length is rather short and that it decreases with increasing concentration of the initiator. This technique has been also used to identify the radiation sensitive link in the CR-39 network. It was found that the length of polyallyl chain is not changed in 60 Co γ-irradiated plastic while the etch rate significantly increases. This shows that the polyallyl chains are relatively inert and not responsible for the radiation sensitivity of CR-39 and that it is the diethyleneglycol dicarbonate links which are damaged by radiation.

Study on the relation between relative sensitivity of CR-39 and electric field strength in electrochemical etching

Abstract By using Mason's formula a simplified electric break-down model is proposed. As a function of the electric field strength (E) in ECE, the relative sensitivity of CR-39 registering tracks of particle is calculated. Some parameters affecting sensitivity are studied. The results from calculation are compared with the experimental data of some authors. the differences among the values of the fitting parameters are discussed.

Plate-out effects in the passive track detectors for radon and its daughters

The paper presents theoretical considerations with regard to the influence of plate-out on the characteristics of passive track detectors of different ‘critical energy’. Results arrived at theoretically have been compared with those obtained experimentally for the four detectors: Bexford-190, LR-115 (II), CN-85, CR-39 for a wide variety of equilibrium states (between decay products and radon). It is shown that, apart from CR-39, all the other detectors are hardly or not all sensitive to plate-out. Curves obtained for the different detector materials are interpreted in the light of the theoretical considerations. The high sensitivity of CR-39 to plate-out is discussed with respect to its practical application in passive track detectors for radon dosimetry.

The effect of thermal treatment after irradiation on the etching properties of CR-39 track detector

ABSTRACT The bulk and track etching properties of CR-39 plastic detector have been investigated under post-irradiation annealing up to 135°C in air or nitrogen. It was found that the bulk etch rate of CR-39 was enhanced twice that of unannealed one by only 2hrs - annealing at temperature around 125°C. While, the etching rate of samples annealed in nitrogen seemed to decrease slightly as the increase of annealing time and temperature. The alpha-to-fission track diameter ratio was reduced and so no gain in sensitivity of CR-39 was observed after annealing in air and nitrogen, respectively.

The forward-backward asymmetry of recoil nuclei in the reaction Al 27(n, α)Na 24

Solid State Nuclear Track Detector (SSNTD) like CR-39 offers a unique opportunity to measure alpha radiations in a complex matrix like high level nuclear waste due to its sensitivity to only alpha radiations in the presence of intense beta–gamma radiation field. There is however a concern about the lower sensitivity of SSNTD when the radiation source is present in solution vis-à-vis solid medium. The sensitivity of CR-39 toward detection of alpha particles homogenously distributed in n-hexane, n-dodecane and n-octanol has been investigated and was found to be better than that obtained in 3 M HNO3.