Ion Implanted Si Detector Research Articles

DIGE differential cross section data for oxygen isotopic analysis

In this work the absolute differential cross sections of the 18O(d,pγ)19O (Eγ = 1376 keV) ,18O(d,nγ)19F (Eγ = 1357 keV) and 16O(d,pγ)17O (Eγ = 871 keV) reactions were measured for the isotopic analysis of oxygen by DIGE technique. The energy of the incident deuterons was varied from 590 to 1994 keV in steps of 10 keV. Gamma-rays and backscattered deuterons were collected simultaneously by an HPGe detector at an angle of 90° and an ion implanted Si detector at a scattering angle of 165° with respect to the beam direction. An anodic Ta216,18O5 thin layer on tantalum was used throughout the cross sections measurement. The validity of obtained cross sections was checked by benchmarking experiment with a thick Y2O3 target. The overall systematic uncertainty of the measured cross section data was estimated to be better than 9%.

Proton induced differential cross sections on 14N and 28Si from 3 to 4 MeV

In this work commercially available self-supporting thin silicon-nitride films were applied to measure the differential cross sections for the reactions 28Si(p,p′γ)28Si (Eγ = 1779 keV) and 14N(p,p′γ)14N (Eγ = 2313 keV) in the proton energy range of 3–4 MeV. For an additional validation of the data, the cross section from the present work and from the literature were integrated and compared to experimental thick target yields. Gamma-rays were detected simultaneously with backscattered particles using a HPGe detector at 55° and an ion implanted Si detector at 135° with respect to the beam direction. As a by-product, differential gamma-ray and particle production cross sections were measured for the first time in the 29Si(p,p′γ)29Si (Eγ = 1273 keV) reaction at 55°, as well as in the natN(p,po)natN, natSi(p,po)natSi and 28Si(p,p1)28Si elastic and inelastic scatterings at 135° from 3 to 4 MeV proton energies.

Differential cross sections measurement of 31P(p,pγ1)31P reaction for PIGE applications

Differential cross sections of proton induced gamma-ray emission from the 31P(p,pγ1)31P (Eγ=1266keV) nuclear reaction were measured in the proton energy range of 1886–3007keV at the laboratory angle of 90°. For these measurements a thin Zn3P2 target evaporated onto a self-supporting C film was used. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to the beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. Simultaneous collection of gamma-rays and RBS spectra is a great advantage of this approach which makes differential cross-section measurements independent on the collected beam charge. The obtained cross-sections were compared with the previously only measured data in the literature. The validity of the measured differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of cross section values was estimated to be better than ±9%.

Measurement of deuteron induced gamma-ray emission differential cross sections on natCl from 1.0 to 2.0 MeV

In this research work, measured differential cross sections for gamma-ray emission from the nuclear reactions 35Cl(d,pγ1-0)36Cl (Eγ=788keV), 35Cl(d,pγ2-0)36Cl (Eγ=1165keV), 37Cl(d,pγ1-0)38Cl (Eγ=671keV) and 37Cl(d,pγ2-0)38Cl (Eγ=755keV) are presented. For these measurements a thin natural BaCl2 target evaporated onto a 50μm-thick Mo foil was used. The gamma-rays and backscattered deuterons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to the beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered deuterons. The validity of the obtained differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of cross section values was estimated to be ±10%.

Measurements of proton induced γ-ray emission cross-sections on Mg from 1.0 to 3.0 MeV

Differential cross-section of proton induced γ-ray emission from the reactions 24Mg(p,p′γ)24Mg (Eγ=1369keV), 25Mg(p,p′γ)25Mg (Eγ=390, 585, 975keV) and 26Mg(p,γ)27Al (Eγ=1014keV) were measured for proton energies from 1 to 3MeV using a 60μg/cm2 Mg target evaporated on a 40μg/cm2 Ag thin film. The γ-rays were collected by a 50% relative efficiency HPGe detector placed at an angle of 90° with respect to the beam direction, while the backscattered protons were collected by an ion implanted Si detector placed at a scattering angle of 165°. Simultaneous collection of γ-ray and RBS spectra is a great advantage of this approach which makes differential cross-section measurements independent on the collected beam charge. Measured cross-section values were compared with the previously reported data in the literature. Absolute γ-ray differential cross-sections were obtained with an overall systematic uncertainty of about ±6% and statistical uncertainty of less than ±5% for proton energies higher than 2.24MeV.

Differential cross sections measurement of 28Si(p,p/γ)28Si and 29Si(p,p/γ)29Si reactions for PIGE applications

Differential cross sections for gamma-ray emission from the 28Si(p,p/γ)28Si (Eγ=1779keV) and the 29Si(p,p/γ)29Si (Eγ=1273keV) nuclear reactions were measured in the energy range of 2.0–3.2MeV and 2.0–3.0MeV, respectively. The thin Si targets were prepared by evaporating natural SiO onto self-supporting Ag films. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. The great advantage of this work is that differential cross sections were obtained with a procedure irrespective of absolute value of the collected beam charge.

Differential cross section measurements of 27Al(p,p/γ)27Al and 27Al(p,αγ)24Mg reactions in the energy range of 1.6–3.0 MeV

In this work measurement of differential cross sections of 27Al(p,p/γ)27Al (Eγ=844, 1014keV) and 27Al(p,αγ)24Mg (Eγ=1369keV) nuclear reactions in the proton energy range of 1.6–3.0MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26μg/cm2 Al onto a 129μg/cm2 self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

Measurement of gamma-ray production cross sections for nuclear reactions 14N(d,pγ)15N and 28Si(d,pγ)29Si

In this work the differential cross sections for gamma-ray emission from the 14N(d,pγ)15N (Eγ=1885, 2297, 7299 and 8310keV) and from the 28Si(d,pγ)29Si (Eγ=1273, 2028, 2426 and 4934keV) were measured simultaneously with the 14N(d,p4,5,6,7)15N differential cross sections and 14N(d,d)14N elastic scattering cross section using a HPGe detector at 55° and an ion implanted Si detector at 135° with respect to the beam direction in the deuteron energy range 0.65–2.0MeV. The target was a thin silicon-nitride film. Gamma-ray angular distribution measurements were performed to determine the possible anisotropy of the gamma-ray emission, and the measured cross section values were converted into total gamma-ray producing cross sections for most of the gamma-ray emissions. The average uncertainties of nitrogen and silicon gamma-ray production cross sections are 5% and 12%, respectively and 8% concerning the particle production cross section of natN(d,d0)natN and 14N(d,p4,5,6,7)15N reactions.

Nanogram amounts of selected rare earth elements measured by AMS

Results are presented from a series of measurements on nanogram quantities of selected rare earth elements. The work was performed at the NRL trace element AMS facility using a multi-cathode cesium-sputtering negative-ion source. The possibility to simultaneously inject, transmit and analyze a relatively broad mass range is a unique feature of our AMS system. The detection system, placed in the focal plane of the split-pole magnetic spectrograph, consists of a combination of position-sensitive microchannel plate and ion-implanted Si detectors. The small amounts of rare earth elements to be measured were chemically extracted from the surface of metallic samples. Calibration curves were built using standards containing 3 and 10ng of the material of interest. Extensive studies were performed to develop a method of normalizing the data by adding known amounts of a given element to the samples and to the standard material. Dedicated software was written to allow for event-by-event data acquisition as well as for data reduction. Results are shown for samples containing from less than 100pg to almost 10ng of material with uncertainties of the order of 15%. Further upgrades of the experimental method are underway.

CHICSi—a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multi-telescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10– 14 μm Si detector, a second 300 μm (or possibly 500 μm ) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 μm Si detector. The telescopes provide full charge separation up to Z=17 and mass resolution up to A=9 in the energy range 0.7– 60A MeV . The thin p-i-n diode detector, etched out from a 280 μm Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution ⩽8%, while the standard 300 μm detectors have ⩽2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10 10 alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm , gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented.

Pulse-height defect in the passivated ion-implanted Si detectors of the INDRA array

The pulse-height defect (PHD) of 36Ar, 58Ni, 129Xe, 181Ta and 197Au ions in the 180 passivated ion-implanted silicon detectors of the INDRA array has been measured. The detectors faced the target with the low electric field side. The charge encoding ensured a low ballistic deficit. Detectors with the same nominal characteristics and electric field strength show a PHD dependence on the individual silicon wafer. They are classified and calibrated by using an empirical parametrization which relates the PHD to the total energy through a Z-depending power law. A PHD analytical formula, based on a simple recombination model, is also proposed. It considers a realistic charge density variation with the position coordinate on the ion path. This new formula is successfully confronted to some experimental data.

Pulse height defect of energetic heavy ions in ion-implanted Si detectors

The pulse height defect in ion-implanted silicon detectors for elastically scattered 93Nb, 100Mo, 116Sn, 120Sn and 129Xe ions, at energies ranging from about 4 to 25 A MeV has been measured. The results are compared with two widely used parametrizations taken from the literature.

High resolution low threshold detector telescopes for multifragmentation studies

A set of compact ionization chamber-Si(IP)CsI(Tl) telescopes for multifragmentation studies are described. These ion chamber telescopes can be used either individually, or to augment the MSU Miniball 4π array. The characteristics of the large-area passivated, ion implanted Si detectors are investigated. Statistics on the overall planarity of these detectors as well as, the thickness of dead layers present at the surface of this type of detectors are examined.

Alpha-particle emission probabilities in the decay of 239Pu

The alpha-particle emission probabilities (Pα) of 239Pu have been measured using material of highest enrichment and radiochemical purity, thin sources produced by vacuum sublimation, and high-resolution α spectroscopy with ion-implanted Si detectors (PIPS). The results for the major emissions are Pα0.07 = 0.7077±0.0014, Pα13 = 0.1711 ± 0.0014 and Pα51 = 0.1194±0.0007, which for the Pα0.07 is about 3.6% lower than the recent evaluated value in the literature.

Resistivity variations in ion implanted silicon detectors

Some ion implanted Si detectors which are specially developed for timing experiments show timing response variations of a few times 100 ps as a function of the position of irradiation. These variations are caused by resistivity variations of a few times 10%. To quantify these resistivity variations, depletion depth studies are performed for a set of detectors. Best timing results are obtained with a high resistivity overdepleted detector.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On the use of thin ion implanted Si detectors in heavy ion experiments

We present test results on the use of thin ion implanted epitaxial Si detectors for registration of low- and medium-energy heavy fragments in nuclear reactions. A linear energy response for very low energy nuclei has been observed. A test of 10 μm + 300 μm telescopes under realistic experimental conditions for heavy ion experiments exhibits the possibilities to use these detectors for the measurements of multifragmentation products.

Charge Multiplication in Silicon Radiation Detectors under Dense Irradiation

Charge multiplication at low field has been studied by fission fragments spectroscopy in ion-implanted Si-detectors. Also, various types of Si-detectors were used at CERN to measure a pulsed muon flux of high density, and again multiplication was observed above a flux threshold which depends on the detector design. In the absence of the gold contact no multiplication occurs.