Silicon PhotoMultipliers, SiPMs, constitute the enabling technology for a diverse and rapidly growing range of applications: medical imaging, experimental physics, and commercial applications are ...only a few examples. In this work, a characterization protocol for SiPM qualification has been applied to Hamamatsu S13161-3050AE-08 SiPM (8 × 8) array in the (−40 ÷ ＋30) °C temperature range. The protocol foresees to measure several parameters: breakdown voltage, quenching resistance, gain, dark count rate and probability of cross-talk. Methods to extract them and their dependence on temperature at fixed overvoltage are shown and the results are discussed.
Prototype of a dual-radiator RICH detector for the Electron–Ion Collider Vallarino, S.; Alexeev, M.; Antonioli, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2024, Letnik:
1058, Številka:
C
Journal Article
A synthetic single crystal diamond based Schottky photodiode was tested at INFN-LNS on the proton beam line (62 MeV) dedicated to the radiation treatment of ocular disease. The diamond detector ...response was studied in terms of pre-irradiation dose, linearity with dose and dose rate, and angular dependence. Depth dose curves were measured for the 62 MeV pristine proton beam and for three unmodulated range-shifted proton beams; furthermore, the spread-out Bragg peak was measured for a modulated therapeutic proton beam. Beam parameters, recommended by the ICRU report 78, were evaluated to analyze depth-dose curves from diamond detector. Measured dose distributions were compared with the corresponding dose distributions acquired with reference plane-parallel ionization chambers. Field size dependence of the output factor (dose per monitor unit) in a therapeutic modulated proton beam was measured with the diamond detector over the range of ocular proton therapy collimator diameters (5-30 mm). Output factors measured with the diamond detector were compared to the ones by a Markus ionization chamber, a Scanditronix Hi-p Si stereotactic diode and a radiochromic EBT2 film. Signal stability within 0.5% was demonstrated for the diamond detector with no need of any pre-irradiation dose. Dose and dose rate dependence of the diamond response was measured: deviations from linearity resulted to be within plus or minus 0.5% over the investigated ranges of 0.5-40.0 Gy and 0.3-30.0 Gy/min respectively. Output factors from diamond detector measured with the smallest collimator (5 mm in diameter) showed a maximum deviation of about 3% with respect to the high resolution radiochromic EBT2 film. Depth-dose curves measured by diamond for unmodulated and modulated beams were in good agreement with those from the reference plane-parallel Markus chamber, with relative differences lower than plus or minus 1% in peak-to-plateau ratios, well within experimental uncertainties. A 2.5% variation in diamond detector response was observed in angular dependence measurements carried-out by varying the proton beam incidence angle in the polar direction. The dosimetric characterization of the tested synthetic single crystal diamond detector clearly indicates its suitability for relative dosimetry in ocular therapy proton beams, with no need of any correction factors accounting for dose rate and linear energy transfer dependence.
The patient dose in radiodiagnostic is currently monitored through an ionizing radiation exposure index named Volume Computed Tomography Dose Index (CTDIvol) and the Dose-Length Product (DLP), ...displayed by CT scanner and measurable through a 100 mm long pencil ionization chamber, inserted in a homogeneous cylindrical PMMA phantom. The phantom is 14 cm long and has a diameter of 16 (32) cm that represents the adult head (body). One of the main flaws of such a method is that it does not return any information on the dose distribution to organs, and the average absorbed dose value, due to the material and dimensions of both the phantom and the ionization chamber, might be either underestimated or overestimated depending upon the patient size. With the aim to obtain complementary information, this work presents a method to estimate organ dose in the thoracic area of an anthropomorphic woman phantom in CT, by employing GafchromicTM XR-QA2 and computational 3-D reconstruction methods. Lungs, heart, and spinal cord have been chosen as a dosimetry case study. XR-QA2 films have been placed between the phantom slabs in the thoracic area and scanned with a multi-slice CT scanner. 2-D and 3-D absorbed dose distributions for each organ have been analyzed, by means of a custom code in Matlab®. Critical aspects in the dose distributions have been found for the spinal-cord case (serial organ) where the dose distribution is non normal and the maximum dose value is ∼30 mGy while a maximum dose value between 26 and 28 mGy has been measured elsewhere.
Aim of this work is evaluate the performance of LiF detectors, TLD-100H, used for both environmental and radiodiagnostic dosimetry. General-Order kinetics (GOK) expressions were applied to ...experimental glow curves of TLDs 100H (LiF. Mg, P, Cu), that were irradiated with an X-ray tube at 140 kVp and reading with a Riso TL/OSL-DA-10 system. New tests were introduced such as the Recuperation test, for evaluate the residual luminescent after each measurement cycle, the Recycling test, aimed to evaluate any systematic errors in the calibration curve and, at last, the Recovery test, with the purpose of evaluate the accuracy of the measured dose from each single dosimeter. The results obtained show an accuracy on the various measured doses ranging from 1.20% to 2.56%.
Polycrystalline (pCVD) and single crystal (scCVD) diamond films grown from Chemical Vapour Deposition (CVD), if sufficiently pure at Raman analysis, are very good materials for beam or flux monitors ...inside accelerators or nuclear reactors. This is because they are very hard to damage in high radiation fields and very resistant to high temperatures. Films of pCVD diamond are, however, not so good as spectroscopy detectors due to inhomogeneities induced by their growth in grains with the consequent presence of grain boundaries which worsen their energy resolution. The latter can be significantly improved by growing scCVD diamond films onto HPHT synthetic diamond substrates. We have shown that it is possible to measure the density of defects inside diamond specimens using as probes suitable penetrating nuclear radiations. With the preliminary results reported here we'll show that, bombarding CVD diamond films grown at Roma “Tor Vergata” with energetic protons and
4He,
6Li and
12C ions produced in the accelerators of Catania laboratories, the pulse height defects are higher than those in silicon detectors and likewise well described by a power law in the deposited energy. Furthermore, we'll show that pulse heights for the same particles seem to depend on the duration of the measurement, thus exhibiting a sort of depolarization of the insulator when exposed to the electric voltage which makes it a particle detector.
Radiation damage of polycrystalline diamond exposed to 62 MeV protons Alemanno, E; Caricato, A P; Chiodini, G ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
730
Journal Article
Recenzirano
We irradiated two diamond detectors with 62 MeV energy proton beam up to an integrated fluence of about 21015 protons/cm2 at INFN-LNS in Catania (Italy). The detectors were made of two high purity ...poly-crystal diamond sensors. The electric contacts of the two diamond sensors were from different sources and made with different techniques: a proprietary DLC/Pt/Au electric contact and our own novel UV Laser technique. We collected 120 GeV and 62 MeV proton beam data, before and after irradiation, respectively, to extract the radiation damage constant of one poly-crystal diamond sensor by using single crystal diamond detector response as reference.
Diamond monocrystalline detectors were used to characterize radiation and particle emission from laser-generated plasma obtained at Laboratori Nazionali del Sud (LNS) and Plasma Asterix Laser Systems ...(PALS) laboratories by using a high power pulsed laser intensity of 10
10
W/cm
2
and 10
16
W/cm
2
, respectively. Al, Ta, Au and CF
2
plasmas were obtained in different irradiation conditions. Diamond detectors permitted to measure UV, X-rays, electrons and ions. Time-of-flight technique was employed to separate in time the different contributions. Results indicate that this detector has some advantages with respect to the others, such as the high energy gap, the high energy resolution, the low background current and the possibility to detect simultaneously photons, electrons and ions.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In this work, we report on the structural characterization of homoepitaxial Microwave Plasma Enhanced CVD diamond grown onto Ib diamond substrates by varying systematically the methane to hydrogen ...ratio in the gas mixture (1–7% CH
4). X-ray diffraction, Raman spectroscopy and photoluminescence (PL) have been used to characterize the diamond samples. Raman measurements pointed out the excellent crystalline quality and phase purity of the specimens. PL measurements in the 1.7–2.7 eV energy range have shown completely flat spectra, excluding the presence of nitrogen-related optical centers. Such results show that the homoepitaxial CVD diamond can be grown, at moderate microwave power (720 W), and at growth rates not too low (∼
1 μm/h) preserving a good quality. Moreover, the homoepitaxial crystals exhibited a strong free-exciton recombination radiation at room temperature even at the highest methane concentration used (7%). Preliminary measurements of the lifetime of the free exciton at room temperature have been also performed. The excitation was produced by a 5 ns pulsed laser irradiation at energies above the diamond band gap. The results have been compared with the structural properties of the samples and correlated with the growth conditions.
Three-layer structures consisting of intrinsic/B-doped homoepitaxial CVD diamond grown onto commercial HPHT Ib substrates have been studied by means of Raman spectroscopy and photoluminescence (PL). ...The intrinsic layers have been deposited, at fixed methane to hydrogen ratio (1%), by systematically changing the substrate temperature (620–820 °C). Raman measurements point out the excellent crystalline quality and phase purity of the samples. Moreover, flat PL spectra in a wide energy range (1.7 eV–2.7 eV) indicate also their great purity. As the free-exciton recombination can be used to further probe the quality of synthetic diamond, measurements of free-exciton emission at room temperature have been also performed. The excitation was produced by a 5 ns pulsed tunable laser irradiation. The results have been compared with the detection characteristics of simple alpha-particle detector prototypes based on the analyzed samples. A clear correlation between excitonic emission and detector sensitivity is demonstrated. On the basis of these results, low methane concentrations (approx. 1% CH
4/H
2) in the deposition gas mixture and intermediate substrate temperatures (approx. 720 °C–770 °C) have been identified as the best working conditions of our growth reactor.
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