Si Surface Barrier Detector Research Articles

SiC and Si detectors comparison for high carbon energy spectrometry

An innovative SiC Schottky junction and a traditional p-n Si surface barrier detector have been compared to detect carbon ions with MeVs kinetic energy. To this, a comparison was performed during Rutherford backscattering spectrometry (RBS) using 2–10 MeV carbon ion beams. The energy resolution and detection efficiency for RBS analysis using the two detectors and their detection electronics are presented.The detector parameters dependencies on the surface passivating layers, ion energy and current dependence, ion penetration depth, detection efficiency, energy resolution, and others are discussed.The comparison of RBS analysis with SiC and Si is investigated highlighting the advantages and disadvantages of using SiC with respect to the traditional Si surface barrier detectors. The two detectors employed for proton, helium and carbon RBS spectrometry of different targets have been also compared on the base of the literature data.

Comparison between conventional Si and new generation of SiC detector for high proton energy spectrometry

A SiC Schottky diode and a Si surface barrier detector have been compared during Rutherford backscattering spectrometry (RBS) using 2–3 MeV proton beams. Both detectors are suited to detect high energetic ions with high-energy resolution for spectroscopic analysis. The correlations between the detector parameters and the surface passivating layers, ion energy and current dependence, ion penetration depth, detection efficiency and energy resolution, are outlined. Comparative RBS analysis performed using SiC and Si detectors has been investigated to highlight the advantages and disadvantages of the use of SiC with respect to the traditional Si junction detector. RBS spectrometry has been carried out using projectiles of proton incident on different targets to analyse their composition and thickness by the detection of the backscattered ions revealed by Si and SiC detectors.

Double-differential cross sections for charged particle emissions from α particle impinging on Al at 230 MeV/u

ABSTRACT Charged particle production from α particle fragmentation reactions was investigated experimentally by measurement of 230-MeV/u α particles bombarding an aluminum target. Double differential cross sections were measured for each ejectile of p, d, t, 3He, and 4He using counter telescopes composed of Si surface barrier detectors and crystal scintillators, which were located at laboratory angles between 15° and 60°. The obtained data were analyzed for comparison with data observed at lower incident energies. The results found the following common characteristics: (1) spectra of proton- and neutron-emission are similar in high energy region at forward angle, (2) triton-to-3He ratio of α-breakup yield is 1:2, which is similar to lower incident energy experiment, and (3) the shape of broad peak formed by 3He and α particles could be explained by the process with collision between induced α particle and target nucleus.

Silicon carbide Schottky diode detector for fusion neutron yields monitoring using associated particle method

The associated particle method is proven to be one of ideal options for D-T fusion neutron detection, acquiring accurate neutron yields by monitoring α particle. Semiconductor detectors can be used to detect α particle for compact size, high energy-resolution, and stable response. SiC detector with high radiation resistance is benefit for long service time in fusion neutron monitoring. In this paper, a SiC Schottky diode detector is used to detect associated α particles for D-T fusion neutron monitoring, and successfully gets accurate neutron yields, being highly consistent with the conventional Si surface barrier detector. It is encouraging to find out SiC detector can afford 2.56 × 109 cm−2 α particles irradiation, with slight performance degradation of dark current and energy resolution, indicating that SiC detector is a promising candidate for fusion neutron detection.

Influence of α-particles irradiation on the properties and performance of silicon semiconductor detectors

Deterioration of the operation parameters of p-type Si surface-barrier detector and Si(Li) p-i-n detector upon irradiation by alpha-particles was investigated. The detectors were irradiated at room temperature up to a total number of the registered α-particles Nα equal to 6 × 109. Prolonged irradiation has resulted in a deterioration of the detectors energy resolution ability and it was found that the increase of α-peaks broadening can be described by a linear function of Nα with a slope Δσ/ΔNα ∼ (1.4–1.8) × 10–9 keV/α for both detectors. Resolution deterioration was associated with the increase of the detectors leakage current, which proceeds linearly with the number of absorbed α-particles with the slope ΔI/ΔNα ∼ (7-17) × 10-17 A/α. The increase of the detectors reverse current was related with appearance of radiation-induced defect level at 0.56 eV above the valence band.

Electrically Active Defects Induced by α‐Particle Irradiation in p‐Type Si Surface Barrier Detector

Herein, the investigation of radiation‐induced defects generated in the Al/SiO2/p‐type FZ Si surface barrier detector upon irradiation with α‐particles at room temperature using capacitance−voltage (C−V) and current deep‐level transient spectroscopy (IDLTS) methods is conducted. The carried out C−V measurements indicate the formation of at least 8 × 1012 cm−3 radiation‐induced acceptor traps at the depth fairly close to that where, according to TRIM simulations, the highest concentration of vacancy‐interstitial pairs is created by the incoming α‐particles. The studies conducted by the current DLTS technique allow to relate the observed increase in the acceptor concentration with the near‐midgap level at E V + 0.56 eV. This level can apparently be associated with V2O defects recognized previously to be responsible for the space−charge sign inversion in the irradiated n‐type Si detectors.

Nuclear Reactions under Irradiation of Deuterated Structures by X Rays

Measurements of emission from nuclear reaction products (neutrons and protons) have been carried out appearing in the deuterated structures of textured CVD diamond, palladium, titanium, and zirconium under irradiation with a beam of X rays using independent methods (neutron detector based on He-3 counters, Si surface-barrier semiconductor detectors and CR-39 track detector). The possibility of enhancement of both DD reaction and multi-particle deuterium fusion by the beam of X rays with energy ranging 20–30 keV in solid deuterated targets has been established. Analysis of X-ray fluorescence spectra of the target bombarded by beams of ions has revealed “additional” peaks, the occurrence of which cannot be related to any of the known elements, and requires separate study.

Study of 50 GeV proton ionization loss by semiconductor detector with smoothly tunable thickness

The possibility of the measurement of proton ionization loss in the Silicon (Si) layer of smoothly tunable thickness was demonstrated in an experiment with a 50-GeV proton beam. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high-voltage power supply was used in the experiment. The measured spectra of ionization loss are discussed and compared with the calculated spectra. The possibilities of research of the evolution of electromagnetic field of ultrarelativistic particles traversing the media interface and the study of dynamics of particles moving in the channeling regime or the volume reflection regime with the use of detectors with smoothly tunable thickness are indicated.

Semiconductor detector with smoothly tunable effective thickness for the study of ionization loss by moderately relativistic electrons

The possibility of measurement of electrons ionization loss in Si layer of smoothly tunable thickness is shown in the proof-of-principle experiment. The Si surface-barrier detector with the depleted layer thickness controlled by the value of high voltage power supply has been used. Ionization loss spectra for electrons emitted by radioactive source 207Bi are presented and discussed. Experimental results for the most probable ionization loss in the Landau spectral peak are compared with theoretical calculations. The possibility of research of evolution of electromagnetic field of ultra-relativistic particles traversing media interface with the use of detectors with smoothly tunable thickness is proposed.

A unique alpha dosimetry technique using Gafchromic EBT3(®) film and feasibility study for an activity calibrator for alpha-emitting radiopharmaceuticals.

To develop an alpha dosimetry technique for activity calibration of alpha-emitting radiopharmaceuticals using the Gafchromic(®) EBT3 (Gaf-EBT3) radiochromic film (International Speciality product, Wayne, NJ). The Gaf-EBT3 has a tissue equivalent radiosensitive layer (approximately 28 μm) sandwiched between two 100-μm thick polyester sheaths, thereby making it insensitive to alpha particles. We have split a Gaf-EBT3 sheet using a surgical scalpel to remove one of the polyester protective layers and covered the radiosensitive layer with thin Mylar(®) foil (Goodfellow Cambridge Limited, Huntingdon, UK) (2.5 μm). Small pieces of modified film were exposed at contact with a 560-Bq thin (241)Am source for 5, 10, 24 and 94 h. The optical density of the films was evaluated using an optical densitometer. The alpha energy spectra of the (241)Am source were recorded using a Si(Li) surface barrier detector. Time-integrated specific alpha surface activity (kBq cm(-2) h) was represented as a function of optical density. By removing one of the 100 μm thick polyester protective layers, the authors have modified the Gaf-EBT3 film to a sensitive alpha dosemeter. The calibration function relevant to a (241)Am reference source was evaluated from the optical densities of the dosemeter foils. Furthermore, calibration functions for important alpha emitters such as (223)Ra, (225)Ac or (210)Bi were parameterized from the (241)Am reference data. The authors have developed and tested the principle of a clinical alpha dosemeter using Gaf-EBT3 radiochromic films originally developed for photon dosimetry. This novel, user-friendly technique could be implemented in quality assurance and calibration procedures of important alpha-emitting radiopharmaceuticals prior to their clinical applications.

Study of an unfolding algorithm for D-T neutron energy spectra measurement using a recoil proton method**Supported by National Natural Science Foundations of China (11375077, 21327801) and National Key Scientific Instrument And Equipment Development Project (2013YQ40861)

A proton recoil method for measuring D-T neutron energy spectra using polyethylene film and a Si(Au) surface barrier detector is presented. An iteration algorithm for unfolding the recoil proton energy spectrum to the neutron energy spectrum is investigated. The response matrices R of the polyethylene film at angles of 0° and 45° were obtained by simulating the recoil proton energy spectra from mono-energetic neutrons using the MCNPX code. With an assumed D-T neutron spectrum, the recoil proton spectra from the polyethylene film at angles of 0° and 45° were also simulated using the MCNPX code. Based on the response matrices R and the simulated recoil proton spectra at 0° and 45°, the respective unfolded neutron spectra were obtained using the iteration algorithm, and compared with the assumed neutron spectrum. The results show that the iteration algorithm method can be applied to unfold the recoil proton energy spectrum to the neutron energy spectrum for D-T neutron energy spectra measurement using the recoil proton method.

Determining the 6Li doped side of a glass scintillator for ultra cold neutrons

Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side 6Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the α and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

The microbeam system at Tohoku University

A microbeam system called MB-I was developed at the Dynamitron laboratory at Tohoku University in 2002 for use in biological applications. Although the system was designed to achieve a submicron beam spot size, parasitic field contamination from tungsten carbide slit chips and an annular Si surface barrier detector have limited the beam spot size to [Formula: see text]. By replacing these components, parasitic field contamination of the system was reduced and the performance of the microbeam system was remarkably improved. A measured beam spot size of [Formula: see text] at a beam current of several tens of pA has been achieved. MB-I has been used for simultaneous in-air/in-vacuum particle-induced X-ray emission (PIXE), Rutherford backscattering spectroscopy (RBS), secondary electron (SE), scanning transmission ion microscopy (STIM) analyses, and three-dimensional PIXE micron computed tomography (PIXEμCT), with applications in various fields. To obtain a higher spatial resolution of several hundred nm and a higher beam current with a resolution of several μm, a triplet lens system was designed and installed in MB-I. The triplet system has a larger demagnification than the existing system; however, it also has larger chromatic and spherical aberration coefficients. Therefore, stricter requirements are imposed on the accelerator performance, particularly the beam brightness and energy stability. In addition to the microbeam, the Dynamitron accelerator was also upgraded to obtain a higher beam brightness. The beam brightness is [Formula: see text], with a half-divergence of 0.07 mrad. The energy resolution of the accelerator was improved by developing a terminal voltage stabilization system (TVSS), to achieve an energy resolution of [Formula: see text]. Thus, the effects of the increased chromatic and spherical aberration were mitigated by restricting the divergence angle, without reducing the beam current. A beam spot size of [Formula: see text] was obtained with a beam current of 150 pA. While the analysis system of MB-I can be used for simultaneous in-air/vacuum PIXE, RBS and STIM analyses, as well as 3D PIXEμCT, without changing the target chamber, changes are required in the experimental setup for these techniques, which is time-consuming, Thus, a new microbeam system, MB-II, was developed. The MB-II is a doublet system and is not equipped with a high-resolution energy analysis system. It is connected to a switching magnet. The beam brightness is [Formula: see text] at a half-divergence of 0.1 mrad and this does not decrease as the beam divergence increases. This property is matched to obtain a higher beam current using the doublet system. With a current of 300 pA, the MB-II provides a higher beam current for a [Formula: see text] beam spot size than is achievable with the MB-I. At present, both microbeam systems are in routine operation at the Dynamitron laboratory.

Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors

Solid State Nuclear Track Detectors of the CR-39∕PM-355 type were irradiated with protons with energies in the range from 0.2 to 8.5 MeV. Their intensities and energies were controlled by a Si surface barrier detector located in an accelerator scattering chamber. The ranges of protons with energies of 6-7 MeV were comparable to the thickness of the PM-355 track detectors. Latent tracks in the polymeric detectors were chemically etched under standard conditions to develop the tracks. Standard optical microscope and scanning electron microscopy techniques were used for surface morphology characterization.

Neutron-induced 63Ni activity and microscopic observation of copper samples exposed to the Hiroshima atomic bomb

Fast neutron activation data for 63Ni in copper samples exposed to the Hiroshima atomic bomb are important in evaluating neutron doses to the survivors. Up to until now, accelerator mass spectrometry and liquid scintillation counting methods have been applied in 63Ni measurements and data were accumulated within 1500m from the hypocenter. The slope of the activation curve versus distance shows reasonable agreement with the calculation result, however, data near the hypocenter are scarce. In the present work, two copper samples obtained from the Atomic bomb dome (155m from the hypocenter) and the Bank of Japan building (392m) were utilized in 63Ni beta-ray measurement with a Si surface barrier detector. Additionally, microscopic observation of the metal surfaces was performed for the first time. Only upper limit of 63Ni production was obtained for copper sample of the Atomic bomb dome. The result of the 63Ni measurement for Bank of Japan building show reasonable agreement with the AMS measurement and to fast neutron activation calculations based on the Dosimetry System 2002 (DS02) neutrons.

Measurements of charge distributions of the fragments in the low energy fission reaction

The measurement for charge distributions of fragments in spontaneous fission 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a ΔΕ−Ε particle telescope, in which a thin grid ionization chamber served as the ΔΕ-section and the E-section was an Au–Si surface barrier detector. The typical physical quantities of fragments, such as mass number and kinetic energies as well as the deposition in the gas ΔΕ detector and E detector were derived from the coincident measurement data. The charge distributions of the light fragments for the fixed mass number A2⁎ and total kinetic energy (TKE) were obtained by the least-squares fits for the response functions of the ΔΕ detector with multi-Gaussian functions representing the different elements. The results of the charge distributions for some typical fragments are shown in this article which indicates that this detection setup has the charge distribution capability of Ζ:ΔΖ>40:1. The experimental method developed in this work for determining the charge distributions of fragments is expected to be employed in the neutron induced fissions of 232Th and 238U or other low energy fission reactions.

Alpha energy resolution enhancement of a Si surface barrier detector

In this work, alpha energy resolution of a Si surface barrier detector was improved. For this purpose, we used constant fraction timing method. Energy resolution enhancement of about 1 % was achieved for alpha peak of 210Po. In order to prove the validity of the timing method, it was applied to the alpha spectrum of 226Ra. It was concluded that proposed method was successful on the energy resolution improvement.

Elastic scattering of 7Li+27Al at several angles in the 7–11MeV energy range

Elastic cross sections for the 7 Li + 27 Al system were measured at laboratory energies between 7 and 11 MeV in steps of 0.25 MeV, and angles between 135° and 170° in steps of 5°. Excitation functions for the elastic scattering were measured using an array of eight Si surface-barrier detectors whereas a solid-state telescope was used to estimate and subtract background from other reactions. Contamination from α particles arising from the 7 Li breakup process at E lab ⩾ 10 MeV makes the use of these energies inadvisable for RBS applications. The present results are compared with previous data obtained at 165° ( E lab ⩽ 6 MeV), 140° and 170° ( E lab ⩽ 8 MeV). The experimental data were analyzed in terms of the Optical Model. Two different energy-independent potentials were found. These optical potentials allow an interpolation with physical meaning to other energies and scattering angles. The experimental cross sections will be uploaded to the IBANDL database.

Proton elastic scattering and proton induced γ-ray emission cross-sections on Na from 2 to 5 MeV

Differential cross-sections for proton elastic scattering on sodium and for γ-ray emission from the reactions 23Na(p,p′γ)23Na (Eγ=440keV and Eγ =1636keV) and 23Na(p,α′γ)20Ne (Eγ =1634keV) were measured for proton energies from 2.2 to 5.2MeV using a 63μg/cm2 NaBr target evaporated on a self-supporting thin C film.The γ-rays were detected by a 38% relative efficiency Ge detector placed at an angle of 135° with respect to the beam direction, while the backscattered protons were collected by a Si surface barrier detector placed at a scattering angle of 150°. Absolute differential cross-sections were obtained with an overall uncertainty estimated to be better than ±6.0% for elastic scattering and ±12% for γ-ray emission, at all the beam energies.To provide a convincing test of the overall validity of the measured elastic scattering cross-section, thick target benchmark experiments at several proton energies are presented.

A proposal design of a multi-hit two-dimensional position-sensitive energy spectrum detector

A new non-linear comparison method of charge-division readout scheme is conceived and the first design of a multi-hit two-dimensional position-sensitive energy spectrum Si(Au) surface barrier detector with a continuous sensitive area is proposed.