Passivated Implanted Planar Silicon Detector Research Articles

A comparison of alpha-particle and gamma-ray spectrometry methods for determination of 235U, 238U and 226Ra activity concentration in samples of coal, slag and fly-ash

In order to compare alpha-particle and gamma-ray spectrometry, the activity concentrations of 235U, 238U and 226Ra in samples of coal, slag and fly-ash from the thermal power plant “Nikola Tesla A”, Serbia, were determined by these two methods. Methods were compared and discussed from the point of view of its precision, difficulty to apply and complexity. Gamma-ray spectrometry was performed with HPGe (High Purity Germanium) spectrometer, while alpha activity was measured by PIPS (Passivated Implanted Planar Silicon) detector. For the alpha-particle spectrometry, the chemical procedures applied were chromatographic resin extraction for uranium isotopes and micro-coprecipitation for 226Ra. Thin alpha sources were prepared by electrodeposition and filtration through polypropylene membrane filter for uranium determination, while filtration technique was performed for radium sources. For the evaluation of the statistical difference between individual measurement results obtained by application of two methods Z - test was used. In order to evaluate the difference between two methods used, paired samples t-test and F-test were applied. Results show that there is no statistical difference between two methods used and that gamma-ray spectrometry is a valid alternative to time consuming alpha spectrometry.

Accuracy comparison of fitting function applied to air-borne alpha detection spectrum

The ability to detect airborne alpha particles in real time could greatly enhance the safety of workers in radioactive environments. To assist in the development of an air-borne detection system, this study sought to overcome the difficulties in spectral analysis caused by the strong interaction of alpha particles with matter. Three modified Gaussian fitting functions were applied to a radon progeny alpha spectrum and cross-referenced to counteract the overlap phenomenon produced by low-tailing of the alpha peak. The radon progeny alpha spectrum was derived using MCNP6 and a PIPS (passivated implanted planar silicon) detector. The radionuclides were determined pertaining to two cases, where case 1 included 220Rn, 216Po, and 212Bi, and case 2 included 222Rn and 218Po. The RMS (root mean square) and reduced chi-square values were compared for accuracy. The convolution of an exponential low-energy tail with a Gaussian distribution equation provided 6.68% lower relative error than when two Gaussian distribution functions were combined according to centroid conditions. The relative error was 0.84% lower than with a Gauss function, indicating a spectrum-peak Gaussian distribution. By constructing the algorithm using this equation, it was possible to obtain high-accuracy analysis data even with low-resolution spectrums in the air.

Characterizing High-Energy Ion Beams With PIPS Detectors

The energy deposited by heavy-ion beams was measured using a passivated implanted planar silicon (PIPS) detector in different facilities. Ion beams at ultrahigh energy lead to the formation of a second, unexpected peak in the deposited energy spectrum at slightly higher energy, in addition to the expected primary peak. Monte Carlo simulations are used to shed light on the origin of this phenomenon and the underlying physical mechanisms. The importance of accounting for secondaries' production in the packaging materials of the diode and the mechanisms at play are highlighted in the discussion of the results.

Simulation of the response of a PIPS detector using GEANT4 code

The main objective of this work is to simulate a PIPS (Passivated Implanted Planar Silicon) detector response by Monte Carlo method and its validation with experimental results. Specifically, we have calculated via simulation the counting efficiency and the energy resolution of a PIPS detector. In order to do this, we have developed a Geant4 application that includes the most relevant physics processes, the geometry, composition and radioactive content of the sample, and the geometry of the PIPS detector and the vacuum chamber. However, some parameters involved in the Monte Carlo simulation are unknown (detector dead layer or sample thickness), and it was mandatory to estimate them through comparisons between experimental and calculated detector responses in order to obtain an accurate simulation of the PIPS detector.To show the validity of the simulated results, we present a comparison of the simulated alpha particle energy spectrum with the experimental one from a uranium dioxide pellet.

239Pu alpha spectrum analysis based on PIPS detector response function and variations with vacuum and distance

Effect factors of the absorption of the source, air, entrance window, and dead layer of a detector must be considered in the measurement of monoenergetic alpha particles, along with statistical noise and other factors that collectively cause the alpha spectrum to exhibit a well-known low-energy tail. Therefore, the establishment of an alpha spectrum detector response function from the perspective of a signaling system must consider the various factors mentioned above. The detector response function is the convolution of an alpha-particle pulse function, two exponential functions, and a Gaussian function, followed by calculation of the parameters of the detector response function using the weighted least-squares fitting method as proposed in this paper. In our experiment, 239Pu alpha spectra were measured by a high-resolution, passivated implanted planar silicon (PIPS) detector at 10 levels of vacuum and 10 source-detector distances. The spectrum-fitting results were excellent as evaluated by reduced Chi-square (χ 2) and correlation coefficients. Finally, the variation of parameters with vacuum level and source-detector distance was studied. Results demonstrate that σ, τ1, and τ2 exhibit no obvious trend of variation with vacuum in the range 2000–20,000 mTorr, and at a confidence level of 95%, the values of τ1 and τ2 decline in a similar fashion with source-detector distance by the power exponential function, while the value of σ declines linearly.

Investigation of X-ray spectral response of D-T fusion produced neutron irradiated PIPS detectors for plasma X-ray diagnostics

This paper describes the fusion-produced neutron irradiation induced changes in the X-ray spectral response of commercially available Passivated Implanted Planar Silicon (PIPS) detectors using the accelerator based D-T generator. After 14.1 MeV neutron irradiation up to a fluence of 3.6× 1010 n/cm2, the energy resolution (i.e. FWHM) of the detectors at room temperature is found to degrade by about 3.8 times that of the pre-irradiated value. From the X-ray spectral characteristics, it has been observed that the room temperature spectral response of PIPS detectors is too poor even at low neutron fluences. Irradiation is also carried out with Am-Be neutron source for studying the effect of scattered neutrons from the reactor walls on the detector performance. Comparative studies of the damage caused by 14.1 MeV neutrons and Am-Be source produced neutrons at the same neutron fluence are carried out by analyzing the irradiated detector characteristics. The degradation in the energy resolution of the detectors is attributed to the radiation induced changes in the detector leakage current. No considerable changes in the full depletion voltage and the effective doping concentration up to the neutron fluence of 3.6× 1010 n/cm2, are observed from the measured C-V characteristics. Partial recovery of the neutron irradiated detector characteristics is discussed.

Numerical Simulation of 14.1 MeV Neutron Irradiation Effects on Electrical Characteristics of PIPS Detector for Plasma X-Ray Tomography

Numerical simulation studies of D-T fusion produced neutron irradiation-induced changes in the electrical characteristics of commercially available Passivated Implanted Planar Silicon (PIPS) detectors (with ρ = 7.4 kΩcm) are carried out using a commercial device simulator for plasma X-ray tomography in nuclear fusion reactors. The proposed radiation damage model is validated by comparing with the experimental data of 14.1 MeV neutron irradiated PIPS detector for fluence up to 3.6 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> n/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The possible changes in the irradiated detector characteristics for higher neutron fluence levels are predicted. Furthermore, the simulated results for higher neutron fluence are validated by comparing with the reported experimental results. The probable deterioration in the X-ray energy response of PIPS detectors is analyzed from the changes in the electrical characteristics due to neutron irradiation. The simulated investigations are also repeated for detectors with different resistivity substrates (4 kΩ cm, and 300 Ωcm) and thin detector structures (100 μm). From the simulation studies, the possible use of the silicon detectors for the plasma X-ray tomography diagnostics is discussed.

High-resolutionαand electron spectroscopy ofCf98249

$\ensuremath{\alpha}$-particle spectra of $^{249}\mathrm{Cf}$ have been measured with a double-focusing magnetic spectrometer and with passivated implanted planar silicon (PIPS) detectors. The conversion-electron spectra of $^{249}\mathrm{Cf}$ have been measured with a cooled Si(Li) detector and with a room-temperature PIPS detector. Precise energies of $\ensuremath{\alpha}$ groups in the decay of $^{249}\mathrm{Cf}$ have been measured with respect to the known energy of $^{250}\mathrm{Cf}$. In addition, $\ensuremath{\alpha}$-electron, $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$, and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence measurements were also performed to determine the spin-parity of the previously known 643.64-keV level. From electron intensities, conversion coefficients of transitions in the daughter $^{245}\mathrm{Cm}$ have been determined. The measured ${L}_{3}$ conversion coefficients of the 333.4- and 388.2-keV transitions are found to be in agreement with the theoretical conversion coefficients for pure $E1$ multipolarity. On the other hand, the $K,{L}_{1}+{L}_{2},M$, and $N$ conversion coefficients are approximately twice the theoretical values for pure $E1$ transitions. These measurements indicate anomalous $E1$ conversion coefficients for the 333.4- and 388.2-keV transitions, as has been pointed out in earlier measurements. The measured conversion coefficient of the 255.5-keV transition gives an $M1$ multipolarity for this transition which establishes a spin-parity of 7/${2}^{\ensuremath{-}}$ and the 7/${2}^{\ensuremath{-}}[743]$ single-particle assignment to the 643.64-keV level.

Method of “Active Correlations” for DSSSD detector application

Real-time PC based algorithm is developed for DSSSD (Double Side Silicon Strip Detector) detector. Brief description of the detection system is also presented. Complete fusion nuclear reaction nat Yt + 48 Ca → 217 Th is used to test this algorithm at 48Ca beam. Example of successful application of a former algorithm for resistive strip PIPS (resistive strip Passivated Implanted Planar Silicon) detector is presented too.

Room-temperature electron spectroscopy of 239Pu and 240Pu

Passivated, implanted, planar silicon (PIPS) detectors have been used for the measurement of electron spectra. The commercially available PIPS detectors, available in thicknesses of 100μm, 300μm, and 500μm, have an energy resolution (FWHM) of ~2.2keV, which is essentially the same as that of PIN diodes. Alpha and electron spectra of mass-separated 239Pu and 240Pu sources have been measured with a 300-μm thick PIPS detector and the electron to alpha ratios for the conversion lines of the 51.62- and 45.24-keV transitions have been determined. A procedure has been developed to determine the amount of 239Pu and 240Pu in a mixed source. The α-particle emission rate of the mixed source is measured, which is the sum of individual rates. From the electron spectrum of the mixed source, measured with the same setup as the alpha spectrum, the rates of 239Pu electron lines are determined. Using the electron rate of the 239Pu line and the electron to alpha ratio measured for the pure source, the α-particle emission rate of 239Pu is determined. The difference from the total α-particle emission rate gives the α-particle emission rate of 240Pu. In addition, electron intensities and conversion coefficients of the 239Pu and 240Pu transitions have been measured.

Monte Carlo simulation of beta radiation response function for semiconductor Si detector

Abstract This paper describes the modeling of the Passivated Implanted Planar Silicon (PIPS) detector for the beta particles response function simulations with the MCNP-5 code. The simulated and measured energy response functions were compared and a good agreement was found in the entire range of energies. The verified model of a PIPS detector was applied in a non-destructive method that determines the activity of beta emitters in the sample with a known geometry and atomic number densities. The procedure for the identification of beta emitters in the samples was also described. Finally, the application of the proposed method for the determination of 137Cs and 90Sr activity in water samples taken from the RA reactor spent fuel storage pools and from the paper filter taken from an air monitor operated during repackaging of spent fuel elements, was presented.

On the comparison of three methods of assessing beam quality for broad beam in vitro cell irradiation

The interaction of charged particles with living matter has recently attracted increasing interest in the field of biomedical applications such as hadron therapy, radioprotection and space radiation biology. Particle accelerators are particularly useful in this area. In vitro radiobiological studies with a broad beam configuration require beam homogeneity. The goal is to produce a dose distribution given to a cell population that is as close to uniform as possible. In this paper, we compare the results of three devices used to assess the beam quality for broad beam irradiation: a passivated implanted planar silicon (PIPS) particle detector, a position-sensitive solid state detector, which is camera-like, and a solid state nuclear track detector (CR39). The first device is a PIPS detector of 300 μm nominal depletion depth and an entrance window with a thickness of about 500 Å. It is collimated with a 0.5 mm aperture and mounted in air on an XY moving table as close as possible to the exit window of the beam line. The second device is a CMOS position-sensitive detector (technological process 0.6 μm AMS CUA), 112 × 112 pixels, with 153 × 153 μm 2 pixel size. It allows the user to rapidly obtain dose uniformity over a surface of 1 × 1 cm 2. During uniformity and dose rate assessment it is placed in air at the PIPS location. For both detectors, beam profile was obtained for various proton fluxes (from ∼5 × 10 4 to 10 6 particles cm −2 s −1). Preliminary tests were made with CR39 using 4 MeV He ++ ions. Results are analysed using Poisson distribution and cell hit probability.

Natural radionuclides in milk from the vicinity of a former uranium mine

Natural radionuclides in milk from farms in the vicinity of a former uranium mine Žirovski vrh in Slovenia, from a farm on the reference location, in powdered milk purchased from Ljubljana shops and in milk intended for infant food, were determined. In the milk samples, 238U, 234U, 226Ra, 210Pb and 210Po were determined. After sample preparation, radiochemical separation and preparation of counting sources, 238U, 234U, 226Ra and 210Po were measured by alpha spectrometric system equipped with passivated implanted planar silicon detectors (PIPS) and 210Pb by a gas-flow proportional counter. Activity concentrations varied from 0.009 to 0.354 Bq/kg dry weight for 238U, 0.019–0.177 Bq/kg dry weight for 234U, 0.041–0.110 Bq/kg dry weight for 226Ra, 0.290–0.652 Bq/kg dry weight for 210Pb and 0.055–0.611 Bq/kg dry weight for 210Po. Assessed combined annual effective doses per unit of intake were from 8.7 to 13.0 μSv/year for adults and from 195 to 648 μSv/year for infants.

Gas electron multiplier (GEM) enhanced ionization chamber for fluorescence detector

Detecting dilute elements in thin materials using extended X-ray absorption fluorescence spectroscopy (EXAFS) method requires a detector capable of high count rate and low noise. For detection of dilute elements, the fluorescence signal amplitude is often overcome by the presence of noise or background interference. In this paper we have used a gas ionization chamber enhanced by a gas electron multiplier (GEM) to amplify the primary ionized electrons due to the X-ray fluorescence of a dilute element. The GEM provides an essentially noise free electron amplification of the signal primary photoelectrons. It provides a larger output current prior to the electronic amplification, allowing a lower gain amplifier with lower electronic circuit noise contribution and hence improved S/ N ratio. In addition, since the signal is produced only by electrons, and not from ion motion, the detector is capable of recording rapidly changing signals. Iron in an arbitrary tree leaf was used as a test sample. This sample was measured using our detector SUBRSAB, and also with Lytle and passivated implanted planar silicon (PIPS) detectors. An improvement in the signal amplitude by a factor of 20 and a factor of 2 are recorded for the proposed detector with respect to the Lytle and PIPS detectors, respectively. Although the gain in signal over the PIPS detector is small for this detector, its lack of sensitivity to light and its low and temperature-independent dark current are further advantages.

Characterization of Si p-i-n diode for scanning transmission ion microanalysis of biological samples

The performance of a silicon p-i-n diode (Hamamatsu S1223-01) for the detection of charged particles was investigated and compared with the response of a standard passivated implanted planar silicon (PIPS) detector. The photodiode was characterized by ion beam induced charge collection with a micrometer spatial resolution using proton and alpha particle beams in the 1–3MeV energy range. Results indicate that homogeneity, energy resolution, and reproducibility of detection of charged particles enable the use of the low cost silicon p-i-n device as a replacement of conventional PIPS detector during scanning transmission ion microanalysis experiments. The Si p-i-n diode detection setup was successfully applied to scanning transmission ion microscopy determination of subcellular compartments on human cancer cultured cells.

Response of a passivated implanted planar silicon (PIPS) detector for heavy ions with energies between 25 and 360 keV

Measurements of the energy response of a passivated implanted planar silicon (PIPS) detector for a variety of ions at low energies are presented. Such measurements are needed for the calibration of a PIPS detector used in a space borne time-of-flight mass spectrometer. Comparisons to similar measurements with state of the art silicon surface barrier (SSB) detectors show a weaker energy response and a much lower noise level of the PIPS detector. A dependence of the energy response on the incident angle of the ions was observed which is attributed to channeling of ions within the silicon crystal of the detector.