429 research outputs found
A Dual-Channel Spectrometer Based on 1mm-Thick SDDs for the Study of Nuclear Beta Decays
No full textWe present the ASPECT-BET project developing a dual-channel SDD-based spectrometer designed to achieve high-precision measurements of beta decays across a broad energy range (spanning from 10 keV to 1 MeV). The adoption of SDDs in electron spectroscopy represents a relatively novel approach, with promising preliminary results already observed in the TRISTAN project, which focuses on accurate beta spectroscopy of Tritium decay. The primary objective of ASPECTBET
is to extend the research, including more energetic radioactive sources to study allowed and forbidden nuclear beta decays. To achieve this goal, we have incorporated larger (8 mm diameter) and thicker (1 mm-thick) detectors to enhance the absorption capability of the
spectrometer, and a CSA featuring a larger feedback capacitance. Furthermore, by utilizing two SDDs arranged one in front of the other, post-acquisition data processing can be applied to eliminate partial energy depositions in detectors caused by undesirable effects such as electron backscattering or escape of characteristic X-rays. An assessment of the energy resolution achieved at the Mn-Kα (5.9 keV)
fluorescence line, obtained by exposing the spectrometer to a 55Fe calibration source, is presented. A FWHM below 200 eV is achieved under conditions of a 1 μs peaking time and cooling at -23 °C, indicating the potential suitability of the spectrometer for high-energy beta decay
studies
Small field correction factors determination for several active detectors using a Monte Carlo method in the Elekta Axesse linac equipped with circular cones
No full textA Monte Carlo (MC) method was used to determine small field output correction factors for several active detectors (Exradin A16, Exradin A26, PTW microLion, PTW microDiamond, Exradin W1 and IBA RAZOR) for an Elekta Axesse linac equipped with circular cones. MC model of the linac was built with the GamBet software, using the Penelope code system. The dose-to-water simulation for each cone, ranging from 5 to 30 mm of diameter size, was used to calculate field factors and the results were validated together with Gafchromic EBT3 film. Output factors (OFs) were measured with the active detectors and correction factors were determined using the MC results. The MC simulations agreed with films within 1.2%. OFs measured with Exradin W1 scintillator were in agreement within 0.8% with MC simulations. The Exradin A16 and A26 microchambers under-responded for small fields relative to the MC (-13.1% and -4.6%, respectively). PTW microLion, IBA RAZOR and PTW microDiamond overestimated the output factor for the smallest field (+3.9%, +5.4 and +7.1%, respectively). The present study pointed out that it is crucial to apply the appropriate correction factors in order to provide accurate measurements in small beams geometry. The results showed that the Exradin W1 can be used for very small field dosimetry without correction factors, which shall be contrariwise employed for other detectors
Development of LGAD sensors at FBK
No full textThe High Luminosity upgrade of the Large Hadron Collider highlighted the need for a time-tagging of tracks with a precision of tens of picoseconds. This requirement motivated the development of radiation hard silicon sensors dedicated to the time-of-interaction measurement of minimum ionizing particles. Low Gain Avalanche Diodes (LGADs) are silicon sensors with internal charge multiplication and are the baseline for the timing systems of the ATLAS and CMS experiments. These sensors use their gain to improve the signal to noise ratio (SNR) of detector systems and have been engineered to withstand the harsh radiation environment of the experiments. Fondazione Bruno Kessler (FBK) developed the LGAD technology through several production runs. The improved SNR and excellent time resolution made LGADs suitable also for medical, X-ray, and space applications. A feature of LGADs is the presence of a termination structure between regions with gain that results in areas without gain between the readout channels, reducing the fill factor of the devices. Different strategies to improve the fill factor of LGADs are being developed, such as double sided LGADs, resistive AC-coupled LGADs, and trench isolated LGADs. This paper summarizes the experience acquired at FBK with the realization of more than ten sensor batches. Selected results in radiation hardness, time resolution, fill factor, and different LGAD applications will be discussed
Development of LGAD sensors at FBK
No full textThe High Luminosity upgrade of the Large Hadron Collider highlighted the need for a time-tagging of tracks with a precision of tens of picoseconds. This requirement motivated the development of radiation hard silicon sensors dedicated to the time-of-interaction measurement of minimum ionizing particles. Low Gain Avalanche Diodes (LGADs) are silicon sensors with internal charge multiplication and are the baseline for the timing systems of the ATLAS and CMS experiments. These sensors use their gain to improve the signal to noise ratio (SNR) of detector systems and have been engineered to withstand the harsh radiation environment of the experiments. Fondazione Bruno Kessler (FBK) developed the LGAD technology through several production runs. The improved SNR and excellent time resolution made LGADs suitable also for medical, X-ray, and space applications. A feature of LGADs is the presence of a termination structure between regions with gain that results in areas without gain between the readout channels, reducing the fill factor of the devices. Different strategies to improve the fill factor of LGADs are being developed, such as double sided LGADs, resistive AC-coupled LGADs, and trench isolated LGADs. This paper summarizes the experience acquired at FBK with the realization of more than ten sensor batches. Selected results in radiation hardness, time resolution, fill factor, and different LGAD applications will be discussed
Single Event Upset tests and failure rate estimation for a front-end ASIC adopted in high-flux-particle therapy applications
No full textA 64 channels Application Specific Integrated Circuit, named TERA09, designed in a 0.35 m technology for particle therapy applications, has been characterized for Single Event Upset probability. TERA09 is a current-to-frequency converter that offers a wide input range, extending from few nA to hundreds of A, with linearity deviations in the order of a few percent. This device operates as front-end readout electronics for parallel plate ionization chambers adopted in clinical applications. This chip is going to be located beside the monitor chamber, thus not directly exposed to the particle beam. For this reason, no radiation hardening techniques were adopted during the microelectronics design. The intent of the test reported in this paper is to predict the TERA09 upset rate probability in a real application scenario. Due to the fact that TERA09 has an extended digital area with registers and counters, it is interesting to estimate the effect of the secondary neutron field produced during the treatment. The radiation damage test took place at the SIRAD facility of the Italian National Institute for Nuclear Physics in Padova, Italy. The SIRAD facility allows to study the CMOS upset rate as a function of the energy deposited during irradiation. By irradiating the chip with ions of different Linear Energy Transfer, it is possible to calculate the single event effect cross-section as a function of the deposited energy. It resulted that the minimum deposited energy in a CMOS silicon sensitive volume of , responsible for a Single Event Upset probability higher than zero, is 690 keV. In the last part of the paper, we calculated the expected upset probability in a typical clinical environment, knowing the fluence of secondary, backward-emitted neutrons. Considering as an example a treatment room located at the CNAO particle therapy center in Pavia, the expected upset rate for TERA09 is events/year. Using a redundant and independent monitor chamber, the upset probability expected during one detector readout is lower than , as explained in the document
Characterization of a silicon detector and front-end electronics prototype for single ion discrimination in hadrontherapy
No full textThe Move-IT research project of the National Institute for Nuclear Physics aims at the study of models for biologically optimized treatment planning systems in particle therapy and the development of dedicated devices for plan verification. On behalf of this collaboration, the Turin medical physics group is working for the development of a new prototype of silicon strips detector. This device, based on 50 μm thin silicon sensors with internal gain, aims to detect the single beam particle and count their number up to 10 9 cm 2 /s fluxes, with a precision ≥ 99%. The prototype detector will cover a 3×3 cm 2 area, segmented in strips. The classic orthogonal strip positioning is used for beam profile measures. At the moment, two types of sensor geometry with different silicon design features have been characterized with laser, radioactive sources and with a clinical proton beam. For what concerns the front-end electronics, the challenging tasks are represented by the charge and dynamic range which are respectively the 3-150 fC and the hundreds of MHz instantaneous rate (at least 100 MHz, 250 MHz ideally). On this purpose, our group is exploring different solutions with the design of two prototypes of custom front-end electronics: one based on a resistive feedback differential transimpedance amplifier and a second one based on a charge sensitive amplifier with gain boost and a discrimination-activated reset of the feedback capacitance. Preliminary results on the ASIC characterization are presented in the following sections
The Role of Etymology in Criminological Science: Dissecting Language Proof
No full textSociology has a branch called criminology. Criminology examines criminal behaviour by evaluating the causes, methods, and preventative measures of crime while taking systemic, social, and individual aspects into consideration. Etymology and criminological science interact to form a specialised but significant field of research. In the domains of law and criminology, language is very important since the exact meaning of words may influence how laws are interpreted and how cases turn out. The study of a word's etymology, or origin and historical evolution, may provide important context for comprehending legislation, legal documents, and terminology used in the criminal justice system. This study of the literature looks at etymology's place in criminological research, with a particular emphasis on how linguistic evidence may be analysed to strengthen cases in court and aid in criminal investigations for this purpose etymological analysis and case studies were used
Single Event Upset tests for a CMOS 0.35 micron front end and readout electronics for high-flux particle detectors
No full textThe Single Event Upset rate of a 64 channels integrated circuit, designed in CMOS $0.35 μm technology, has been measured and analyzed at the SIRAD facility of the Italian National Institute for Nuclear Physics (INFN). The chip, named TERA09, is a current to frequency converter designed to readout monitor chambers in particle therapy. In this field, the accelerator development is moving toward compact solutions providing high-intensity pulsed-beams. The TERA09 chip is capable to operate in a wide input current range, from few nA to hundreds of μA, with linearity deviations in the order of few percent. The chip is designed to be located aside of the monitoring chambers, far from the therapeutic beam, and no protection from data corruption from single events was implemented in its design. However, considering the relatively large area of the chip covered by data registers and the secondary neutrons field produced during the irradiation, the potential exposure to data corruption by Single Event Effect phenomena need to be addressed. The aim of the tests at SIRAD is to study the upset rate as a function of the energy deposited by single events by irradiating the chip with ions of different LET. From the analysis of the data it is possible to predict the single event effect cross-section in a clinical environment and estimate the readout failure probability in a real application scenario
A single ion discriminator ASIC prototype for particle therapy applications
No full textIn the framework of the development of future advanced treatment modalities in charged particle therapy, the use of silicon sensors is an appealing alternative to gas ionization chambers commonly used for beam monitoring. A prototype of a device, based on Low-Gain Avalanche Diode (LGAD) sensors with thickness, is being developed to discriminate and count single beam particles. This paper describes the design and characterization of ABACUS, an innovative multi-channel ASIC prototype for LGAD readout, based on a fast amplifier with self-reset capabilities. The design goals aim at detecting charge pulses in a wide range, from 4 fC to 150 fC, up to 70 MHz instantaneous rates, with a dead time of about 10 ns or less and efficiency larger than 98%. The characterization results indicate that even at the lowest input charge the signal-to-noise ratio is 15, high enough to keep full efficiency and preventing fake counts from the electronics noise. The dead time was found to be in the range between 5 ns and 10 ns, allowing to reach a full counting efficiency up to instantaneous rates of 70 MHz or larger, depending on the input charge
Development and characterization of large area LGADs for space applications
No full textLow Gain Avalanche Diodes (LGADs) are silicon detectors that use the impact ionization process to achieve gain values of about O(10) and timing resolution of O(30 ps) to detect Minimum Ionizing Particles. In High Energy Physics, the state-of-the-art LGADs foreseen for timing layers feature an active thickness of 50 μm and a channel size in the order of O(1 mm2). Space-based experiments could benefit from a Time-of-Flight system composed by these sensors to distinguish between primary and secondary charged particles hits in the tracker. Scaling up the technology to match the typical channel area of the micro-strip sensors used in spaceborne experiments deteriorates the timing capabilities of the LGADs due, in first approximation, to the increased capacitance. In this study, pad sensors with thickness 50, 100, and 150 μm are investigated, featuring different gain layer profiles, designed to address variation in capacitance. Various layouts are also compared to see their impact on the time resolution. Characterization of leakage current and capacitance as a function of the bias voltage, along with Transient Current Technique, and radioactive source measurements are used to evaluate the performances of these devices. By evaluating gain, noise, and jitter, this work demonstrates the feasibility of designing 1 cm2 LGADs with a jitter as low as 80 ps. Additionally, the study examines signal propagation and uniformity, as the channel size significantly influence there characteristics and their relevance to timing resolution
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