Identification Of Heavy Ions Research Articles

Phosphate glasses for identification of heavy ions

Some problems in nuclear physics and cosmic-ray astrophysics require a detector that can precisely identify one type of heavily ionizing particle against a background of other particles of higher or lower ionization rate. Films of polymers such as bisphenol acetone polycarbonate (for example, Lexan), polyethylene terephthalate (for example, Cronar) and allyl diglycol polycarbonate (for example, CR-39) are most commonly used for this purpose1. For some new applications, track detectors made of phosphate glass of suitable composition, chemically etched in an optimally chosen reagent, are proving to be much better than polymeric track detectors. One such application is the study of rare radioactive decay modes involving the occasional emission of a specific energetic nuclide such as 24Ne or 34Si in an enormous background of alpha particles or spontaneous fission fragments2,3. Another is the possibility of resolving neighbouring elements, or isotopes of a given element, in relativistic cosmic rays when the fractional difference in charge or mass is very small, as with Pb (Z = 82) and Bi (Z = 83), or 56Fe and 57Fe4. Here we present the results of a study of the relative sensitivities of a large number of phosphate glasses to relativistic ions of U, Au and La, indicating which ones are particularly useful for particle identification.

On heavy ion identification in a mineral track detector

Abstract Experiments have been carried out on tracks of high energy U (and, very recently, Au) ions in olivine. The results offer an explanation for the lack of success of previous attempts to derive Ultraheavy Cosmic Ray composition from the study of tracks in meteorites. They also suggest how such experiments could be improved to achieve real ion identification capabilities. The methods we are testing are described and illustrated.

Epitaxial integrated d E1 − d E2 silicon detectors

Epitaxial integrated d E 1 − d E 2 silicon detectors have been developed by using the multilayer epitaxial crystal growth technique combined with the chemical preferential etching technique. These detectors are useful for eliminating events affected by channeling and blocking effects in the identification of heavy ions using multiple detector telescope systems. Characteristics of d E detectors of the integrated d E 1 − d E 2 type are confirmed to as good as those of integrated E − d E detectors.

Range sensitive telescope detector

A telescope for the identification of heavy ions over an extended energy range is described. The energy loss Δ E is measured with an ionisation chamber supplied with the range-sensitive charge collection system. The particle residual energy E can be measured with a solid state detector. Two modes of operation are available: a standard ΔEt− E identification, or a charge integration along the track with a continuous resistivity anode. By a proper formation of this resistivity, one can obtain an identification signal proportional to the Z value in a large range of incident energies.

Developments of heavy-ion gas detectors at LNL

The most important developments in gaseous detectors at LNL are reviewed. Some aspects of timing, pulse height and position resolutions of avalanche counters are reported. The experimental work on heavy-ion identification by Bragg curve spectroscopy is summarized.

Electrolytical measurements for heavy ion identification in plastic detectors

A new technique is presented where the time needed to etch a given track length through a detector foil is a measure for the energy loss of the ion. We report on results of 20Ne-ions in CR-39 with an accuracy better than 1% and on a self stopping system for the measuring current.

Particle identification through the measurement of the Bragg curve centroid

A new method of particle identification of heavy ions through the measurement of the Bragg curve centroid and particle energy has been developed using a gas ionization chamber with a resistive anode layer. Z-resolutions comparable to the conventional ΔE-E counter telescope could be rather easily attained.

Performance of a Bragg curve detector for heavy ion identification

By using Bragg curve spectroscopy, one can measure atomic number and energy of high energy heavy ions stopping in a gas-filled ionization chamber with longitudinal electric field. In this paper, we report on the results obtained with an isobutane filled detector. An energy resolution of 0.8% fwhm and a Z resolution of 2.7% fwhm were achieved for elastically scattered 300 MeV 40Ar ions. We study the Bragg peak amplitude dependence on the energy of the incoming ions, a dependence presumably due to the Frisch grid screening inefficiency. The corrected Bragg peak spectrum of inelastically scattered 300 MeV 40Ar ions exhibits a satisfactory Z separation around Z=18.

Time-of-flight telescope for mass identification of heavy ions

A time-of-flight telescope, employing microchannel plate electron multipliers as start detector and a silicon surface barrier as stop detector, is presented. The measured intrinsic time resolution is 160 ps FWHM for262Cf α-particles and 235 ps FWHM for252Cf fission fragments selected in the energy rangeE = (79÷80) MeV. The contribution of each fragment mass is estimated to be 120 ps. The measured detection efficiencies are ≿95%, depending on ion masses.

Mass identification of heavy ions by time of flight techniques

A time-zero detector to be used in a time-of-flight-energy telescope is presented. With such a device a time resolution of 150 ps and a mass resolution δM/M = 1 80 are achieved in heavy ion experiments.

Time determination in a magnetic spectrometer with a large area thin plastic scintillator

Abstract Mass identification of heavy ions ( M ⩽100) has been obtained in a magnetic spectrometer by the time-of-light method. The start signal was given by a large area thin plastic scintillator placed at the entrance of the spectrometer, and bent to correct for the differences in path lengths.

The weizmann institute heavy-ion identification system

A high resolution and highly efficient heavy-ion identification system is described. The system is based on the kinematic coincidence technique. It uses a multiwire proportional counter, a drift chamber and a parallel plate avalanche counter in order to measure the time-of-flight and the position x, y of both fragments emitted in a binary reaction. The performances of the system are presented using the interactions of 16 O + 16 O as an example.

A compact time-zero detector for mass identification of heavy ions

A time-zero detector to be used in a time of flight-energy telescope for the mass identification of heavy ions is described. The secondary electrons emitted from a thin carbon foil during the passage of the ions are accelerated and bent through 90° by electrostatic fields onto a micro-channel-plate electron multiplier. A time resolution of 150 ps and a mass resolution ΔM M = 1 80 are obtained in heavy ion experiments.

Real-time digital pre-analysis for heavy ion identification: Two hardware algorithms

This paper describes the realization of two common algorithms for heavy ion identification implemented with special purpose hardware. For the multiplicative algorithm the trigger is produced in 560 ns; for the “range” algorithm, in 400 ns. These times allow an efficient real-time pre-analysis.

An analogue particle identifier for heavy ions

A high accuracy analogue device for particle identification of heavy ions using the time-of-flight of the ions and their energy or their position in the focal plane of a magnetic spectrometer is described.

A gas detector system for mass and charge identification of heavy ions

A gas detector system (GDS) consisting of a long ionisation chamber (LIC) and a parallel plate avalanche counter (PPAC) which is realized as a transmission detector in front of the LIC is described. The PPAC measures together with the rebuncher and the pulsing system of the Heidelberg MP tandem accelerator the time of flight, the LIC the energy E and the specific energy loss ΔE of the heavy ions. The LIC is characterised by its active depth of 80 cm, which results in an energy resolution of 0.4% for 150 MeV 32S ions. The energy resolution is limited by the energy loss straggling in the entrance windows. From measurements of heavy ion straggling in polypropylene foils a semi-empirical formula is derived. The time resolution of the system is 230 ps. The energy loss resolution is 3.6% for 150 MeV 32S ions. It is limited by the energy loss straggling in the gas. The active area is 20 cm 2. The coordinates of the incident ions can be measured to a precision of 1 mm.

Element and isotope separation for a heavy ion cosmic ray telescope with large geometric factor

The charge and mass response of a space-borne solid state cosmic ray detection system for heavy ions is discussed. Its large geometrical factor causes pathlength variations due to the large opening angle of the telescope, and to the thickness non-uniformity of the thin large area detectors. Accelerator experiments with 147 MeV and 402 MeV 20Ne beams have been performed and the effect of the pathlength variations in addition to the intrinsic energy-straggling distribution on the heavy ion identification is presented.

Heavy Ion Identification System by Using a Gas Proportional Counter Telescope

Heavy Ion Identification System by Using a Gas Proportional Counter Telescope

An analysis of the power law type algorithm for identification of heavy ions by using the modified Zaidins empirical range-energy relationship

The properties of the power law type particle identification formula are studied as a function of the detector thickness. The result shows that the formula is applicable to energies lower than one could expect from the deviations of the power law of the range-energy relationship for heavy ions. For this analysis, the empirical range-energy formula proposed by Zaidins has been improved in order to obtain a better estimate of the range, especially for heavy ions. Experimental results of heavy ion identification thus obtained are also shown.

Dosimetry of cosmic particles in nuclear emulsions for the apollo 16, 17 and apollo-soyouz-test-project experiments (1972–1975)

Abstract In the Biostack I, II and III experiments flown on the Apollo 16 and 17 and ASTP missions, nuclear emulsion plates have been used for the first time for heavy-ion identification in connection with biological layers. After the calibration step using the heavy ions available at the Bevalac at Berkeley, the nuclear emulsion can give dosimetric results for the heavy ions hitting biological materials. These results have been sent for exploitation to the biological laboratories of Toulouse, Frankfurt and Marburg. We summarize all the dosimetric results in the field of heavy-ion tracks and nuclear stars induced by cosmic-ray particles. The last results from Biobloc (December, 1975) are presented.