CsI Target Research Articles

Transmutation of radioactive cesium and iodine using gamma-radiation from light nuclei under proton bombardment

In this work, we propose a novel approach to transmute long-lived radionuclides, by using γ-radiation emitted in the bombardment of light nuclei by low-energy proton beams. We used Monte Carlo simulations to demonstrate the feasibility of photo-transmutation of hazardous radioactive cesium and iodine by the γ-radiation from proton capture in 7Li. The dependence of the γ-ray the proton energy (in the region of the 441 keV resonance) and on the thickness of 7Li target are presented. For 10 mA proton beam, the γ-ray yield is estimated to be 2.1 × 109 s−1. When such γ-radiation irradiates on the CsI target, the transmutation yield reaches 5 × 107 s−1, which is comparable to the value resulted by the state-of-the-art Laser-Compton scattering γ-ray source. The proton-induced resonance γ-ray source can therefore be a promising approach for nuclear waste management.

Photon and neutron hybrid transmutation for radioactive cesium and iodine

This work is concerned with transmutation of the highly toxic radioactive Cs-135 and Cs-137, which are extremely difficult to transmute in the conventional neutron fields, together with I-129. A novel strategy of photon and neutron hybrid transmutation has been proposed for a CsI target. An optimized laser-Compton scattering (LCS) source is used to generate energetic gamma-rays, which are then directed to central CsI target for photonuclear (γ,n) transmutation. Energetic neutrons resulting from the (γ,n) reactions are scattered through moderator into a surrounding CsI blanket targets where they undergo (n,γ) transmutation. In this study, design parameters such as LCS spectrum, target dimensions and configurations have been optimized to enhance the effectiveness of the hybrid transmutation method. In addition, the CsI target configuration has also been optimized to remove heat deposited in the central target. From the results, it has been concluded that the hybrid transmutation has promising applications for the radioactive waste management.

Evaluation of the neutron background in CsI target for WIMP direct detection when using a reactor neutrino detector as a neutron veto system

A direct WIMP (Weakly Interacting Massive Particle) detector with a neutron veto system is designed to better reject neutrons. An experimental configuration is studied in the present paper: a WIMP detectors with CsI(Na) target is placed inside a reactor neutrino detector. The neutrino detector is used as a neutron veto device. The neutron background for the experimental design has been estimated using the Geant4 simulation. The results show that the neutron background can decrease to O(0.01) events per year per tonne of CsI(Na). We calculate the sensitivity to spin-independent WIMP-nucleon elastic scattering. An exposure of one tonne $\times$ year could reach a cross-section of about 3$\times$$10^{-11}$ pb.

Simulation and Measurement of Quenching and Channeling Effects in CsI(Tl) for Dark Matter Search

In order to understand the scintillation characteristics of nuclear recoil events in CsI(Tl) crystals and for application to the analysis of Dark Matter (DM) searches, we study quenching and channeling effects with simulations of recoil ion motion in CsI(Tl) and experiments using neutrons impinging on the crystal. The electronic energy loss versus penetration depth of recoil ions in a CsI(Tl) target are simulated by the SRIM and MARLOWE programs and modified by the application of a measured scintillation efficiency function. They are used to produce quenching factors as a function of recoil energy. The application of the MARLOWE code to a monocrystalline target yields a light yield distribution including tails which are correlated with ions' enhanced ranges. The 2.4 MeV pulsed neutrons impinging on a monocrystalline CsI(Tl) target and an array of neutron detectors located at different scattering angles are used to measure the light yield distribution and the status of the measurement is reported.

Photon, Electron and Secondary Ion Emission from Single C(60) keV Impacts.

This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C(60) keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C(60) projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution.

Application of high-energy polarised beam energy dispersive X-ray fluorescence spectrometry to cadmium determination in saline solutions

In the present work, the analytical performance of a methodology based on a preconcentration using activated thin layers followed by high-energy polarised beam energy-dispersive XRF spectrometry (HE-P-EDXRF) for the determination of trace amounts of Cd in saline solutions is presented. Linear calibration curves were obtained over the range 5–8000 μg L−1 of Cd. When comparing the developed method to the direct analysis of Cd in sea water, the detection limits were improved by several orders of magnitude, with values of 2.25 μg L−1 (Al2O3 target) and 0.075 μg L−1 (CsI target), respectively. The accuracy was checked by analyzing spiked natural sea water at Cd concentrations of 20, 100 and 600 μg L−1 and results were compared to those obtained with anodic stripping voltametry and no significant differences at the 95% confidence level were found. The method has a good reproducibility over the investigated period of time and the precision of the method was better than 10%.

Ion-beam sputtering deposition of CsI thin films

Stoichiometric CsI thin films were deposited by Ar ion-beam sputtering of a CsI target at room temperature. The sputtered 100-nm thick CsI films obtained were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and quantum efficiency (QE) measurements. As it was expected, the chemical, morphological, crystalline and photo-emissive properties of CsI films obtained depended on the deposition parameters. Comparison with results obtained for evaporated CsI films indicated that surface morphology, i.e., the effective photo-emissive surface area, is one of the important parameters in influencing the QE .

Sublinear effect in light emission from cesium iodide bombarded by keV polyatomic projectiles

Our experiments examined light emission from a CsI target bombarded with polyatomic projectiles [H n +, (NaF) n Na +, with n=1,2; Na +, Cs 2I +, Cs +] at 5–30 keV impact energies. The light emission increases with primary ion velocity as ( V − V th) α , where V th is a velocity threshold. The number of photons emitted under one cluster impact increases with the number of atoms in the projectile, displaying a sublinear effect, similar to that reported elsewhere for electron emission. The model of sweeping out electrons has been applied to explain and calculate the observed effect.

Fast heavy ion induced photon emission from organic solids and plasma desorption mass spectrometry

Fission fragments from a 252Cf source have been used to study fast heavy ion induced desorption of ions and luminescence in the wavelength region 200–680 nm from samples of Csl, the amino acids valine, isoleucine and tyrosine, and of the peptide substance P. All samples emit photons under fast heavy ion bombardment. Most of the emission is confined to the near-UV region and within narrow time profiles. Analysis of the fast decay regions of the time profiles show that all the compounds have at least a fast and a slow decay component, both in the nanosecond region. The use of such narrow photon signals as start time markers for time-of-flight measurements (TOF) has been demonstrated. As the photon signal is derived directly from the desorption event it gives the true number of starts for a secondary ion TOF spectrum. Characteristics of the photon emission from a CsI target together with correlation studies between the desorbed secondary ions and the photon signal indicate that the light emission is from the bulk of the material and not correlated with the secondary ions.

Secondary ion correlations in plasma desorption mass spectrometry as a function of fission fragment energy

Coincidence counting techniques in conjunction with time-of-flight mass spectrometry (TOF-MS) have been applied to the study of correlations between secondary ions desorbed by 252Cf fission fragments. The average energies of the projectiles were decreased by the interposition of thin foils between a 252Cf radioactive source and a CsI target. The co-emission of the secondary ions was examined as a function of projectile energy after each foil. The correlation coefficients were observed to increase with decreasing average energy of the projectiles.

Simultaneous detection of secondary ions and photons produced by the impact of keV polyatomic ions

(CsI) n I −( n=0−3), low mass organic negative clusters, and H −, in the 20–46 keV energy range, have been used in time-of-flight secondary ion mass spectrometry (TOF-SIMS) experiments to study the relationships between secondary ion and photon emission from a surface. We report on the simultaneous detection of secondary ions and photons produced by the impact of keV polyatomic ions. Our results indicate that, for a CsI target, secondary ions and photons are produced independently of each other through different mechanisms. Secondary ion emission is strongly dependent upon the complexity of the primary ion, i.e. monoatomic or polyatomic. However, photon emission appears to be independent of the primary ion's complexity and depends primarily upon the velocity of the primary ion. Unlike the secondary ion yields, no yield enhancements for the photons were observed due to polyatomic primary ions. Only broad band light emission from the bulk of the target was observed; no line emissions from sputtered species were detected. We compare the yields of both secondary ions and photons that were collected simultaneously, and present a simple model that describes the observed photon yields as a function of both the electronic and nuclear stopping powers of the primary ion.

Detection of large molecular ions by secondary ion and secondary electrom emission

Secondary ion and secondary electron emission has been investigated in a tandem time-of-flight mass spectrometer using incident molecular ions produced by laser desorption as primary ions. Measurements of the ratio of secondary electrons to secondary ions from a stainless steel target were made with a range of projectile masses and energies so that the separate dependenc on velocity and mass could be determined. The projectiles ranged in mass from about 300 to 6000 u, and in energy from 300 eV to 30 keV. Secondary accelerating voltages down to 20 V were used to reduce spurious contributions to the electron intensity caused by fragmentation of the projectiles or by grid effects. The electron-to-ion ratio is determined almost entirely by the velocity of the projectile; it is largely insensitive to the mass (for a given velocity). The ratio at first with decreasing velocity but appears to approach a constant value of about 0.1 below a velocity of ≈ 1.4 × 10 6 cm s −1 (≈1 eV u −1). A strong increase in the absolute electron yield and in the electron-to-ion ratio was observed for a fresh CsI target compared to a stainless steel target.

Magnetic moment measurement of theCs129112−isomer in a CsI cubic environment

The g factor of the 575-keV 11/2/sup -/ isomer in /sup 129/Cs has been measured by the time differential perturbed angular distribution technique using the /sup 127/I(..cap alpha..,2n) /sup 129/Cs reaction with a thick CsI target to maintain alignment. A value of g = + 1.191 +- 0.018 was obtained, which is consistent after M1 core-polarization corrections with a predominantly 1h/sub 11/2/ quasiproton structure for this state. The experiment also yielded a remeasurement of the mean lifetime of the isomer as tau = 1059 +- 33 nsec.

Fragmentation cross-section of relativistic oxygen ions and determination of overlap parameter

Fragmentation cross-section of16O relativistic ions, at two different energies, was measured in CsI crystal. An experiment designed basically to study primary cosmic ray nuclei, was exposed to monoenergetic beam of16O ions of bevatron. Fragmentation of the ions was observed in a two layer CsI target. Each CsI crystal was 1 inch thick.

Fragmentation cross sections of 2.1-GeV/nucleonC12andO16ions

A tungsten-scintillator ionization spectrometer (1000 g/${\mathrm{cm}}^{2}$ total depth) has been exposed to 2.1-GeV/nucleon $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ ions at the Bevatron. Fragmentations of the incident ions could be observed in a five-layer CsI target (each layer 9 g/${\mathrm{cm}}^{2}$ thick) and in five tungstenscintillator layers (each 13 g/${\mathrm{cm}}^{2}$ thick). The number of fragmentations in each of these layers has been used to determine the total fragmentation cross sections. The Bradt-Peters overlap parameters are consistent with zero when calculated using these cross sections and a value of ${r}_{0}=1.25\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ cm.

Note: The approximate calculation of fracture time for thin spherical shells subject to internal blast loading

Fission fragments from a 252Cf source have been used to study fast heavy ion induced desorption of ions and luminescence in the wavelength region 200–680 nm from samples of Csl, the amino acids valine, isoleucine and tyrosine, and of the peptide substance P. All samples emit photons under fast heavy ion bombardment. Most of the emission is confined to the near-UV region and within narrow time profiles. Analysis of the fast decay regions of the time profiles show that all the compounds have at least a fast and a slow decay component, both in the nanosecond region. The use of such narrow photon signals as start time markers for time-of-flight measurements (TOF) has been demonstrated. As the photon signal is derived directly from the desorption event it gives the true number of starts for a secondary ion TOF spectrum. Characteristics of the photon emission from a CsI target together with correlation studies between the desorbed secondary ions and the photon signal indicate that the light emission is from the bulk of the material and not correlated with the secondary ions.