Beta-ray Spectrometer Research Articles

Estimation of TL Response of Phosphors to Beta Rays by Measuring Energy Spectrum of Absorbed Beta Particles

Abstract The beta energy absorbed in the thermoluminescent (TL) phosphor was determined directly from the difference in the pulse height spectrum between incident and transmitted beta particles to and from the phosphor, in order to examine the sensitivity of commercially available powdered phosphors, LiF (TLD-100) and CaF2:Dy (TLD-200), to beta particles. A beta ray spectrometer equipped with plastic scintillator and GM tube was used, instead of an extrapolation chamber. The TL sensitivity of LiF powder to the beta particles emitted from sources of 45Ca, 204Tl, 90Sr/90Y, and 32P was found to be 0.18-0.22 Gy.µJ-1 per 5 mg of phosphor expressed in equivalent air kerma of 60Co gamma rays. The sensivity of CaF2:Dy powder to beta rays was approximately 8 times that of LiF. It is suggested that a beta dosemeter capable of estimating the beta energy or a two-element or multi-element dosemeter is necessary for measurement of beta dose in a deep skin.

Estimation of TL Response of Phosphors to Beta Rays by Measuring Energy Spectrum of Absorbed Beta Particles

The beta energy absorbed in the thermoluminescent (TL) phosphor was determined directly from the difference in the pulse height spectrum between incident and transmitted beta particles to and from the phosphor, in order to examine the sensitivity of commercially available powdered phosphors, LiF (TLD-100) and CaF2:Dy (TLD-200), to beta particles. A beta ray spectrometer equipped with plastic scintillator and GM tube was used, instead of an extrapolation chamber. The TL sensitivity of LiF powder to the beta particles emitted from sources of 45Ca, 204Tl, 90Sr/90Y, and 32P was found to be 0.18-0.22 Gy.µJ-1 per 5 mg of phosphor expressed in equivalent air kerma of 60Co gamma rays. The sensivity of CaF2:Dy powder to beta rays was approximately 8 times that of LiF. It is suggested that a beta dosemeter capable of estimating the beta energy or a two-element or multi-element dosemeter is necessary for measurement of beta dose in a deep skin.

Semiconductor telescope spectrometer for beta-ray spectra

A telescope beta-ray spectrometer consisting of a 3 mm thick Si(Li) ΔE plus a 5 mm thick Ge(HP) E detector was built and tested. Simplicity and insensitivity to γ-rays (when operated in a coincidence mode) make the device well suited to β+ and β− end-point energy measurements, and it can also be used in on-line studies of very short-lived β emitters. Due to a number of effects associated with the interactions of the β-particles with the spectrometer, the calibration curves for β+ and β− end-point energies were found to be different and were determined using several well-known β activities. As an application of the method, the 4493gRu β+ end-point energy was measured. The result, 5315 (85) keV, is in good agreement with the prediction from the mass-systematics of the 1977 Mass tables.

Measuring relativistic electrons in the undergraduate laboratory

An experiment is described for measuring the momentum and energy of relativistic electrons from a radioactive beta source. Electrons are momentum-selected in a simple beta-ray spectrometer and then measured for energy with a surface barrier detector. The results illustrate to students a clear confirmation of the relativistic energy–momentum relationship, and provide an accurate measure of the rest mass of electrons and the speed of light. The apparatus we describe also can be used in experiments for measuring beta spectra.

A position sensitive proportional counter for a beta-ray spectrometer II

A position senstive proportional counter employing resistive charge division has been improved for use on the focal plane of an iron-free π√2 beta-ray spectrometer. This counter consists of three Nichrome anode wires of 10 μm in diameter which are stretched in parallel and connected in series. This allows three position spectra, divided in the direction of the magnetic field of the spectrometer, to be simultaneously measured, each of which covers the momentum range of about 4%. The spatial resolution (fwhm) obtained is 0.5 mm between 100 and 1000 keV, which corresponds to a momentum resolution of 0.016%. The momentum resolution obtained at 45 keV is 0.047%, and that above 10 keV is higher than 0.1%. The incident angles ( ø e and θ e) of electrons can be roughly obtained by placing a similar counter behind the first one and simultaneously measuring two-dimensional positions ( x 1, z 1) and ( x 2, z 2), respectively. With this two-counter system, a very low natural background count is obtained, smaller than one count/hour per fwhm of a peak. Experimental studies have effectively been made by using this counter to examine the focusing properties of this spectrometer, and these reveal that this spectrometer is suitable for use in the broad momentum range of about 4% if very high resolution, better than 0.08%, is not required.

Shape factor analysis of beta transitions in Pm-149

Shape factor analysis of the beta transitions in149Pm is carried out for the first time, employing an intermediate image beta ray spectrometer. The ambigous situation arising from the disagreement between reported values in end point energies and intensities of the beta transitions is clarified. An attempt was made to evaluate the NME, for the 780 keV beta transition, using Simms formalism.

The Measurement of β-Spectra with an Iron-Free, Double Focusing π√2 Spectrometer

An account is given of an experimental study of the instrumental distortions of continuous spectra measured on an iron-free double-focusing π√2 beta-ray spectrometer, and of the steps taken to reduce such distortions.

A position sensitive proportional counter for a beta-ray spectrometer

A position sensitive proportional counter employing resistive charge division was constructed for use in the focal plane of an iron-free π√2 beta-ray spectrometer ( r 0 = 75 cm). The momentum range measured at a time was about 4% and the relatively good linearity was obtained. The momentum resolution (fwhm) obtained was 0.046% at 1 MeV and 0.063% at 130 keV. The very low natural background counts were also obtained.

Mössbauer studies of the morin transition in bulk and micro-crystalline α - Fe 2O +3

This chapter discusses the conversion coefficient of a few gamma-ray transitions. The method of the conversion coefficient determination is to simultaneously measure the electron spectrum and the unconverted gamma-ray spectrum from a standard source and then measure the electron and the unconverted gamma-ray spectrum of the source in question in an identical geometry. The standard source is so chosen as to have a gamma ray with well-determined conversion coefficient of energy as nearly equal as possible to the gamma ray of the source under study. In a study described in the chapter, the electron spectra were studied in a Gerholm-type beta-ray spectrometer and in a Si-Li spectrometer. The gamma-ray spectra were measured in a NaI (Tl) spectrometer or a Ge-Li spectrometer. In the studies of In113, In115, Xe129, the 412-keV transition in Hg195 from Au198 was utilized, and in the study of Xe133, Cs137 source was used as a standard.

Nuclear magnetic resonance study of La 3X compounds and related phases

This chapter discusses the conversion coefficient of a few gamma-ray transitions. The method of the conversion coefficient determination is to simultaneously measure the electron spectrum and the unconverted gamma-ray spectrum from a standard source and then measure the electron and the unconverted gamma-ray spectrum of the source in question in an identical geometry. The standard source is so chosen as to have a gamma ray with well-determined conversion coefficient of energy as nearly equal as possible to the gamma ray of the source under study. In a study described in the chapter, the electron spectra were studied in a Gerholm-type beta-ray spectrometer and in a Si-Li spectrometer. The gamma-ray spectra were measured in a NaI (Tl) spectrometer or a Ge-Li spectrometer. In the studies of In113, In115, Xe129, the 412-keV transition in Hg195 from Au198 was utilized, and in the study of Xe133, Cs137 source was used as a standard.

Shape of the 935 keV beta transition of143Pr

The beta spectrum shape of the 7/2+ → 7/2− beta transition in the decay of143Pr is measured employing a thoroughly tested intermediate image beta ray spectrometer of the Siegbahn-Slatis type and using the source produced by irradiation of highly enriched stable142Ce sample. The spectrum exhibits a definite energy dependence and is well fitted with shape factorC(W) = 1 − (0·057 ± 0·006)W whereW is in m0c2 units for an end point energy of 935 ± 2 keV agreeing well with the results of Hamiltonet al and Spejweskiet al and disagreeing with the results of Persson and Reynolds. The single particle configurations for the low lying levels of143Pr could not give quantitative results.

Spectral shape studies in the beta decay of192Ir

The spectral shapes of the beta groups feeding the 3+ and 4+ levels of 192Pt in the decay of 192Ir are analysed employing a Siegbahn-Slatis beta ray spectrometer in the coincidence mode of operation. These two beta transitions with end-point energies 535+or-2 keV and 666+or-2 keV are found to exhibit similar characteristics of statistical shapes within the experimental uncertainties. The shapes are in accordance with the xi approximation, thus confirming the first forbidden nature of the beta transition feeding the 3+ and 4+ levels of 162Pt and in turn favouring a negative parity for the ground state of 192Ir. The results seem to support the description of the 4+ and 3+ levels in 192Pt as the two-phonon and three-phonon quadrupole vibrational levels.

Shape of the 1110 keV beta transition of143Ce and spin of the 351 keV level in the143Pr

A careful measurement of the shape of the 1110 keV beta transition to the 351 keV level of 143Pr in the decay of 143Ce has been made using a Siegbahn-Slatis beta ray spectrometer of intermediate-image type and a slow-fast coincidence system. Enriched 142Ce samples were used to produce the active 143Ce sources. The statistical shape of the beta transition from the 3/2- ground state of 143Ce to the 351 keV level of 143Pr has confirmed the spin and parity of the 351 keV level as 3/2+.

Nuclear Structure Study of 150Sm. II. Decay of 150Pm

Energies and relative intensities of gamma transitions following the decay of 150 Pm were measured with Ge(Li) detectors and 94 gamma rays were observed. The half-life of 150 Pm was determined to be 161.9±0.9 min. Gamma-gamma coincidence and gamma-gamma anticoincidence measurements were performed. From these measurements the 1670 keV, 2371 keV and 2700 keV levels are proposed and the 2679 keV level is excluded. From beta-gamma coincidence measurements the beta-ray feeding to the ground state was found. By using a \(\sqrt{2}\pi\) beta-ray spectrometer, the beta-ray maximum energy of the transition to the first excited state was determined to be 3120±20 keV and the intensity ratio of the ground-state transition to this transition was 0.0858±0.0043. From gamma-gamma angular correlation measurements E2/M1 or M2/E1 mixing ratios of several gamma rays were obtained.

Introduction to Experimental Nuclear Physics

R M Singru New Delhi: Wiley Eastern Private 1974 (distrib. J Wiley) 1975 pp xii + 162 price £2.50 This book is essentially a companion for a laboratory course at MSc or final year undergraduate level in experimental nuclear physics. It first reviews briefly the physics of nuclear reactions and the interaction of radiation with matter, and then discusses alpha, beta and gamma ray spectrometers as well as general radiation detectors.

Conversion-electron and nuclear lifetime measurements with an in-beam iron-free orange spectrometer

An orange type iron-free beta-ray spectrometer is installed at the isochronous cyclotron of the University of Bonn for on-line experiments. The principal features of the experimental arrangement are described. Conversion-electron and nuclear lifetime measurements and special techniques for the background reduction are reported and some results are presented.

Small order deviation of91Y beta spectrum

The negatron spectrum of the 58d 91Y isotope has been analyzed with a thoroughly tested intermediate image beta ray spectrometer. The shape factor analysis was performed with exact Fermi functions and screening corrections. The end point energy of this (1/2- to 5/2+) transition was found to be (1545+or-2 keV). The experimental shape factor was weighted least square fitted to a linear correction term C(W)=k(1-0.009 W) and a hyperbolic term C(W)=k(1-0.028/W). This present measurement is clearly in disagreement with the large hyperbolic form reported by Langer et al. (1949).

A 12-channel magnetic beta-ray spectrometer for quick measurements

A 12-channel magnetic beta-ray spectrometer for quick measurements

Low energy transitions in the decay of155Tb

Internal conversion electrons of low energy from the decay of 5.6 day 155Tb have been studied using a high resolution, iron-free beta-ray spectrometer. The existence of a 10.49 keV transition has been confirmed.

Positron impact inner shell ionization

The positron impact ionization cross section for theK-shell was determined in the case of Ni, Y and Ag at 670 and 490 keV as well as for theL-shell in the case of Yb, Ta, Au and Pb at 490 keV using a beta-ray spectrometer as a source of monoenergetic electrons and anX-e+ coincidence arrangement. The results for theK-shell are compared with the theoretical calculations according to Kolbenstvedt and with the earlier experimental values.