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Timestamp: 2019-04-26 14:17:46+00:00

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Abstract: Publication date: Available online 20 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Andrea Jeremie The SuperNEMO experiment will study 82Se to look for neutrinoless double beta decays (0νββ), proof of the Majorana nature of neutrinos. SuperNEMO inherits the tracking-calorimetry technique of NEMO-3, allowing for a clear determination of event kinematics, while aiming for an improved background suppression and 0νββ sensitivity. A demonstrator module is currently starting operation. The ββ emitting source, ∼7 kg of 82Se in thin foils, is surrounded by a 0.5 meter long helium tracking chamber with 2000 Geiger cells. A 4π gamma catcher and electron calorimeter, made of plastic scintillators with an energy resolution of 7.8% (FWHM) at 1 MeV, surrounds the tracker. The ultra low radioactivity demonstrator is constructed and installed in the Modane Underground Laboratory in the Frejus Tunnel under the French-Italian Alps.
Abstract: Publication date: Available online 20 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Düren, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig, E. Etzelmüller, K. Föhl The DIRC technology (Detection of Internally Reflected Cherenkov light) offers an excellent possibility to minimize the form factor of Cherenkov detectors in hermetic high energy detectors. The PANDA experiment at FAIR in Germany will combine a barrel-shaped DIRC with a disc-shaped DIRC to cover an angular range of 5 to 140 degrees. Particle identification for pions and kaons with a separation power of 3 standard deviations or more will be provided for momenta between 0.5 GeV/c and 3.5 GeV in the barrel region and up to 4 GeV/c in the forward region. Even though the concept is simple, the design and construction of a DIRC is challenging. High precision optics and mechanics are required to maintain the angular information of the Cherenkov photons during multiple internal reflections and to focus the individual photons onto position sensitive photon detectors. These sensors must combine high efficiencies for single photons with low dark count rates and good timing resolution at high rates. The choice of radiation hard fused silica for the optical material and of MCP-PMT photon sensors is essential for DIRC detectors to survive in an environment of radiation and strong magnetic field. The two DIRC detectors differ in the focusing optics, in the treatment of chromatic dispersion and in the electronic readout systems. The technical design of the two DIRC detectors and their validation by testing prototypes in a mixed particle beam at CERN are presented.
Abstract: Publication date: Available online 20 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): A.Yu. Barnyakov, M.Yu. Barnyakov, V.S. Bobrovnikov, A.R. Buzykaev, A.F. Danilyuk, A.A. Katcin, S.A. Kononov, E.A. Kravchenko, I.A. Kuyanov, A.P. Onuchin, I.V. Ovtin Aerogel for different types of Cherenkov detectors is produced by a collaboration of Budker Institute of Nuclear Physics and Boreskov Institute of Catalysis during more than two decades. So far only the production of two sizes was possible in large numbers: 50 × 50 and 115 × 115 mm2. This work is devoted to the development of the production technology of large scale aerogel radiators for use in the Ring-imaging Cherenkov (RICH) detectors. These detectors require additional parameters to be controlled for each aerogel tile during production. Procedures of measurement of the aerogel tiles refractive index, the light scattering length, the upper surface flatness are described.
Abstract: Publication date: Available online 20 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): S.L. Lalitha, A.C.C. Villari, R. Witgen, C. Snow, S. Nash, T. Summers, C. Alleman The Re-Accelerator (ReA3) facility at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) delivers rare isotope and stable beams ranging from 0.3 MeV/u to 6 MeV/u to experimental end stations. The High Energy Beam Transport (HEBT) line into the ReA3 experimental hall houses several quadrupole magnets, dipole magnets, and combined function horizontal and vertical corrector magnets. All of these are iron-dominated, resistive type magnets. This paper describes the magnetic performance of 45°dipole magnets installed in both the vertical and horizontal section of the ReA3 beamline. The computed field map and the derived data provide a reference for the operational setting of the magnet and input for the beam optics study. The field measured by both Hall and NMR probes agrees well with the calculations suggesting that the magnet performance meets the design specification.
Abstract: Publication date: Available online 19 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): J.Y. Chen, C.H. Chen, M.S. Chiu, P.J. Chou, C.C. Kuo, C.C. Liang, Y.C. Liu, H.J. Tsai, F.H. Tseng A stable, reliable and well-calibrated beam position monitor (BPM) system is essential for a safe and reproducible operation of accelerators. The BPM system enables the measurement of important machine and beam parameters, such as the Twiss parameters, and helps to avoid damage to accelerator components by high-energy particle beams or radiation. In this paper, we discuss a new BPM calibration scheme tested at the Taiwan Photon Source (TPS). By altering the current in a single horizontal or vertical corrector magnet, we generate an orbit distortion with respect to the nominal reference orbit. The difference orbit is measured by observing the change of the beam position at each BPM pickup location as a function of the corrector current. The analog BPM signals are digitized by analog-to-digital converters (ADC), giving raw, non-calibrated beam position data for each BPM. By comparison of the beam orbit response in terms of raw ADC data from each BPM with the expected beam displacement we can calibrate the beam position monitors. Moreover, because of limited setup time available after a long shutdown, this new procedure acts as a fast, easy way to calibrate the BPM system.
Abstract: Publication date: Available online 25 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): A. Papanestis Ring Imaging Cherenkov Detectors (RICH) play a significant role in particle and nuclear physics experiments providing particle identification. They work exceptionally well for hadron identification as there are few other techniques that can differentiate between pions kaons and protons in the multi-GeV/c momentum range. This article is a review of detectors using Cherenkov light imaging viewed from a historical perspective and following the evolution of the techniques and technologies.
Abstract: Publication date: Available online 25 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Alan Janos, Stephen Payne, Natalia Zaitseva, Michael Lance, Richard T. Kouzes, Patrick L. Feng, Nicholas Myllenbeck, Gregory C. Slovik, Monojoy Goswami Polyvinyl toluene (PVT) plastic is often used to make gamma ray sensitive scintillators and is used in many important applications. For example, PVT is used to scan recycled steel going into a plant to be processed. It is also used in personnel portals to scan employees, and is used at the borders of many countries to scan cargo and cars passing through. In recent years, it was discovered that PVT can become degraded when it absorbs water and then is subjected to daily temperature swings, as is evidence by a reduction in scintillation light. Water absorption by PVT was notionally associated with temporary fogging (i.e., a rapid decrease in opacity which was reversible over time) and permanent fogging (i.e., permanent crack-like defects) and was for some time suspected to be the leading cause of the fogging due to circumstantial evidence. However, definitive proof was not established and in particular the specific mechanisms by which water entered the plastic and ultimately created temporary and permanent point-like defects was not fully understood. This paper is an overview of an effort initiated to reveal the fundamental root cause and also the dynamics of the fogging and degradation processes. This understanding is important not only to solve degradation problems for PVT in fielded systems, but also (1) to provide direction for future procurements for new equipment, and (2) to provide direction for future R&D efforts into advanced plastics with enhanced spectroscopic capabilities or dual particle gamma/neutron capabilities. Unexpected outcomes of this investigation included 1) the capability to predict the onset of fogging based on models using weather data alone, and (2) new modified formulations of PVT and PS which are fog-resistant. This paper gives an overview of the water uptake and associated mechanisms for various compositions, characterization of resulting temporary and permanent defects, predictive modeling of fogging, and possible solutions including encapsulation, heaters and new formulations. While this paper is an overview of the root cause analysis and solution, five accompanying papers [Refs. 1–5] from the same conference (SORMA 2018) delve further into the details and also expand upon the scope of what will be reported herein.
Abstract: Publication date: Available online 21 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): S. Abovyan, D. Cieri, V. Danielyan, M. Fras, Ph. Gadow, O. Kortner, S. Kortner, H. Kroha, F. Müller, S. Nowak, R. Richter, K. Schmidt-Sommerfeld Single muon triggers are crucial for the physics programmes as hadron collider experiments. To be sensitive to electroweak processes, single muon triggers with transverse momentum thresholds down to 20 GeV and dimuon triggers with even lower thresholds are required. In order to keep the rates of these triggers at an acceptable level these triggers have to be highly selective, i.e. they must have small accidental trigger rates and sharp trigger turn-on curves. The muon systems of the LHC experiments and experiments at future colliders like FCC-hh will use two muon chamber systems for the muon trigger, fast trigger chambers like RPCs with coarse spatial resolution and much slower precision chambers like drift–tube chambers with high spatial resolution. The data of the trigger chambers are used to identify the bunch crossing in which the muon was created and for a rough momentum measurement while the precise measurements of the muon trajectory by the precision chambers are ideal for an accurate muon momentum measurement. A concept for the muon trigger of the baseline detector for the FCC-hh which exploits the precision measurements of drift–tube chambers is presented including the description and the test of a compact muon track reconstruction algorithm.
Abstract: Publication date: Available online 19 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Artem Brovko, Arie Ruzin In the last decade Cd1−xMnxTe (CMT) has been considered as a very promising material for room-temperature radiation detectors. Manganese has a better segregation compared to that of zinc in Cd1−xZnxTe (CZT), in addition MnTe has a wider bandgap than ZnTe enabling broader band “tunability” in the ternary alloy. In this work, we provided a general comparison of these materials grown in similar conditions, focusing, on material composition uniformity and electric properties under dark conditions. Results of material uniformity analyses clearly confirm better homogeneity of CMT crystals, both laterally and in-depth. In addition to material studies, the current–voltage (I–V) characteristics of both In/CZT/In and In/CMT/In metal–semiconductor–metal (MSM) structures were characterized. The results revealed significantly lower variations in contact-to-contact currents in CMT compared to that in CZT (10% and 25% variance, respectively). The temperature behavior of I–V in In/CZT/In and In/CMT/In devices was investigated with calculation of dark current activation energy. The activation energies of dark current mechanisms in CMT were found to be similar at both polarities, whereas there was a 0.2 eV polarity-related difference in CZT based structures.
Abstract: Publication date: Available online 14 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): J. Adamczewski-Musch, P. Akishin, J. Bendarouach, C. Deveaux, M. Dürr, J. Eschke, M. Faul, J. Förtsch, J. Friese, J. Heep, C. Höhne, D. Ivanishchev, K.-H. Kampert, L. Kochenda, P. Kravtsov, I. Kres, S. Lebedev, E. Lebedeva, S. Linev, T. Mahmoud The upgraded HADES RICH detector, as well as the future CBM RICH detector, will both use the same Hamamatsu H12700 Multianode PMTs read out by the newly developed DiRICH FPGA-TDC readout chain for MAPMTs and MCPs. The upgrade of the HADES RICH photon detector has meanwhile been completed, and we are now looking forward to the upcoming physics run in spring 2019. A brief overview on the status of both detector projects is given and supplemented with the recent test-beam results which confirmed the functionality of the DiRICH development before the start of the mass-production of all DiRICH components needed for the HADES RICH upgrade.
Abstract: Publication date: Available online 13 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): V.L. Ivanov, G.V. Fedotovich, A.V. Anisenkov, A.A. Grebenuk, A.A. Kozyrev, A.A. Ruban, K. Yu. Mikhailov This paper describes a currently being developed procedure of the charged particle identification for CMD-3 detector, installed at the VEPP-2000 collider. The procedure is based on the application of the boosted decision trees classification method, and uses as input variables the specific energy losses of charged particles in the 14 layers of the liquid Xenon calorimeter. The performance of the procedure is demonstrated by an example of the extraction of events of e+e−→K+K−(γ) process in the center of mass energy range from 1.28 to 1.65 GeV.
Abstract: Publication date: Available online 11 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): J. Agarwala, C. Chatterjee, G. Cicala, A. Cicuttin, P. Ciliberti, M.L. Crespo, S. Dalla Torre, S. Dasgupta, M. Gregori, S. Levorato, G. Menon, F. Tessarotto, A. Valentini, L. Velardi, Y. Zhao Identification of high momentum hadrons at the future EIC is crucial, gaseous RICH detectors are therefore viable option. Compact collider setups impose to construct RICHes with small radiator length, hence significantly limiting the number of detected photons. More photons can be detected in the far UV region, using a windowless RICH approach. QE of CsI degrades under strong irradiation and air contamination. Nanodiamond based photocathodes (PCs) are being developed as an alternative to CsI. Recent development of layers of hydrogenated nanodiamond powders as an alternative photosensitive material and their performance, when coupled to the THick Gaseous Electron Multipliers (THGEM)-based detectors, are the objects of an ongoing R&D. We report about the initial phase of our studies.
Abstract: Publication date: Available online 9 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Iván Sidelnik, Hernán Asorey, Nicolás Guarin, Mauricio Suaréz Durán, Fabricio Alcalde Bessia, Luis Horacio Arnaldi, Mariano Gómez Berisso, José Lipovetzky, Martín Pérez, Miguel Sofo Haro, Juan Jerónimo Blostein In this work we show the neutron detection capabilities of a water Cherenkov detector (WCD). The experiments presented here were performed using a simple WCD with a single photomultiplier tube (PMT) and a 252Cf neutron source. We compared the use of pure water and water with non contaminant additive as the detection volume. We show that fast neutrons from the 252Cf source can be detected over the flux of atmospheric particles background. Our first estimation for the neutron detection efficiency is at the level of (19)% for pure water and (44)% for the water with the additive. We also present the simulation of the response of the WCD to neutrons using a simulated 252Cf source. We implemented a detailed model of the WCD and of the neutron source spectra using Geant 4. The results of our simulations show the detailed mechanism for the detection of neutrons using WCD and support the experimental evidences presented. Since both active volumes studied, H2O pure and with additive, are cheap, non-toxic and easily accessible materials, the results obtained are of interest for the development of large neutron detectors for different applications. Of special importance are those related with space weather phenomena as well as those for the detection of special nuclear materials. We conclude that WCD used as neutron detectors can be a complementary tool for standard neutron monitors based on 3He.
Abstract: Publication date: Available online 8 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): F.L. Kuang, Z. Li, Z.L. Long, M.W. Liu One-dimensional modeling and simulations of the electric and weighting fields have been systematically carried out for 2D-Planar-Electrode and 3D type detectors. Poisson and Laplace equations have been solved analytically in Cartesian and cylindrical coordinates with well defined boundary conditions. It has been found that the electric field profile and full depletion voltage depend in general on the detector effective doping density (Neff) and electrode spacing (λC), while the weighting field depends only on the electrode spacing and relative geometry size of the collecting electrode with respect to the electrode spacing. For 2D-Planar-Electrode strip and pixel detectors, the full depletion voltage will be somewhat higher than that of 2D pad detectors, and the weighting field will be more concentrated near the collecting electrode duo to the “small pixel” effect. For 3D-Trench-Electrode (cylindrical type) detectors, however, exact one-dimensional solutions have been obtained for electric and weighting fields. The results are compared to those obtained for 2D-Planar-Electrode pad detectors and conventional 3D-Column-Electrode detectors.
Abstract: Publication date: Available online 7 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Ichiro Adachi Silica aerogels have been used widely in high-energy and nuclear physics experiments. Recent developments of highly transparent aerogels have further enabled the utilization of Cherenkov radiators in RICH counters for many experiments. This paper reviews the progress of high-quality aerogels by describing the two optical parameters of transmittance and refractive index, and some issues in its application will be presented.
Abstract: Publication date: Available online 28 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Hee-Joung Kim, Donghoon Lee Recently, low-dose medical imaging attracts a significant interest owing to the harmfulness of ionized radiations including X-rays. However, when the radiation dose is reduced during the medical image acquisition process, a significant quantum noise is commonly generated. The purpose of this study is to develop a deep-learning-based image-denoising method for low-dose chest imaging, which is a commonly performed medical imaging for diagnosis. Conditional generative adversarial networks (CGANs) were used in the development of the denoising algorithm. In order to train the deep-learning model, we used the SPIE American-Association-of-Physicists-in-Medicine lung-CT-challenge, and Lung-Image-Database-Consortium and Image-Database-Resource-Initiative databases. The obtained image demonstrated that the proposed method achieved an excellent image quality by removing the noise component. Compared with conventional denoising algorithms such as the total-variation (TV) minimization and non-local means (NLM), the proposed method exhibited a superior quality of the obtained images. Losses of image information, detrimental in medical diagnoses, occurred in the medical images obtained using conventional denoising algorithms. Unlike the conventional denoising algorithms, the proposed algorithm restored the corrupted image resolution owing to image noise. The quantitative evaluation through structure similarity index measure (SSIM) demonstrated the superiority of the proposed method over the conventional methods. The SSIM of the proposed method was improved by 1.5 and 2.5 times, compared to those of the NLM and TV methods, respectively. Therefore, we developed a denoising algorithm for medical imaging with CGAN, which is one of the latest deep-learning structures, for low-dose chest images. The proposed denoising method is expected to contribute to the improvement of image quality and reduction of the patient dose.
Abstract: Publication date: Available online 26 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Luis Otiniano, Iván Sidelnik, Lago Collaboration The Latin American Giant Observatory (LAGO) consists of a network of water Cherenkov detectors installed in the Andean region at various latitudes, from Sierra Negra in México 18° 59′ N to the Antarctic Peninsula 64° 14′ S 56° 38′ W and altitudes from Lima, Peru at 20 m.a.s.l. to Chacaltaya, Bolivia at 5400 m.a.s.l. The detectors of the network are built on the basis of commercial water tanks, so they have several geometries (cylindrical in general) and different methods of water purification. The LAGO network of detectors also spans a wide range of geomagnetic rigidity cut offs and atmospheric absorption depths. All these features, along with their manufacturing differences, generates different structures in the atmospheric radiation spectra measured by our detectors. One of the main scientific goals of LAGO is to measure the temporal evolution of the flow of secondary particles at ground level. The atmospheric flux produced by the interaction of cosmic rays with the atmosphere at different sites is measured to study the solar modulation of galactic cosmic rays. In the present work we describe the features of a web monitor system developed to integrate, monitor and share the data of the LAGO detectors and discuss the criteria used to estimate the signals left by the secondary particles at the detector, which are based on a novel semi-analytical method that combines simulations of the total cosmic ray spectrum and the detector’s response. We also show the detector calibration method applied on three detectors of the network, including the one operated in the Machu Picchu Base (62° 05′ S 58° 28′ W) during the last Peruvian scientific campaign in Antarctica (January 2018). Finally, we review observation of a Forbush decrease measured in the detectors using this calibration technique.
Abstract: Publication date: Available online 26 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): D.F. Alaroui, E.M. Johnston, M.J. Farquharson The present study was implemented using two X-ray detection systems; a monochromatic X-ray system for X-ray Fluorescence (XRF) and Angular Dispersive X-ray Diffraction (ADXRD) techniques, and a combined Polarized Energy Dispersive X-ray Fluorescence (PEDXRF) and Energy Dispersive X-ray Diffraction (EDXRD) system. As both of these systems involve different techniques, the primary objective of this study was to evaluate the performance and accuracy of each system using results achieved from XRF measurements. The assessment of the two systems was carried out by investigating tissues samples containing invasive ductal carcinoma (IDC) of the breast and normal surrounding breast tissues. The results established from the two XRF systems are in a very good agreement with each other. The statistical analysis reveals a significant and measurable increase (p < 0.01) in the concentration of K, Ca, Zn, Rb and Fe (p < 0.05) in the tumorous tissue when compared with the healthy tissue. However, the levels of Cl, Cu and Br attained by both systems have not demonstrated a statistically significant difference between the normal and cancerous tissues. Investigating the structural components of the same breast tissues using each of the X-ray Diffraction (XRD) spectrometers incorporated in both systems indicated a statistically significant difference in the components of normal and malignant samples. Furthermore, the results have shown a significant increase in the fibrous and water contents of the tumour tissue at p < 0.01, and a significant increase in the adipose content of the normal tissue at (p < 0.01). The results acquired from both XRD approaches were shown to be statistically compatible with each other. Overall, the comparisons between the two X-ray detection systems have shown improved results for the combined PEDXRF and EDXRD system for the purpose of classifying normal and tumour breast tissues.
Abstract: Publication date: Available online 25 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): A. Amorese, C. Langini, G. Dellea, K. Kummer, N.B. Brookes, L. Braicovich, G. Ghiringhelli The spatial resolution achieved in many back-illuminated Charge Coupled Device (CCD) x-ray detectors is limited by the charge spread over the pixels. For low flux measurements charge-cloud centroiding methods can achieve sub-pixel spatial resolution. Experimental measurements have been performed testing the performance of commercially available soft x-ray CCD detectors (Amorese et al., 2019). In this technical note the centroiding methods used and the numerical tests performed to test the method are described. Finally, more advanced corrective algorithms are discussed.
Abstract: Publication date: Available online 23 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): S.S. Khokhlov, A.G. Bogdanov, V.A. Khomyakov, V.V. Kindin, R.P. Kokoulin, A.A. Petrukhin, V.V. Shutenko, I.I. Yashin Cascade showers induced by muons have been studied in the Cherenkov water detector NEVOD with a dense spatial lattice of quasi-spherical measuring modules. The cascades from near-horizontal muons with tracks determined by means of the coordinate-tracking detector were investigated. The results of measurements of the spatial distribution of Cherenkov radiation from cascade particles in such events are presented.
Abstract: Publication date: Available online 22 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Kelsey Stadnikia, Kristofer Henderson, Sanjeev Koppal, Andreas Enqvist Data fusion between 3D vision sensors and radiological sensors can enable data improvements and novel applications for nuclear safeguards. While the radiological sensors allow for nuclear threat detection, the addition of a 3D vision sensor can allow for improved threat detection when using its ability to track objects in a scene. Ten measurements were taken that involved three to four people walking in a room where one of the persons carried a Cf-252 source in a backpack. A data-fusion algorithm was used to correlate the radiological and vision data. The vision trajectory with the highest correlation value was selected as the trajectory carrying the radiological material. Filtering and refining the radiological and vision data was also explored in search of improvements. For unaltered data, the data-fusion approach correctly identified to the source-carrying trajectory for all ten measurements in all cases except when using data where counting statistics were low or the signal-to-background ratio was low. Filtering and refining the data improved the correlation values for all trajectories as expected. The presented algorithm has proven to be an effective means of data fusion between the two different types of sensor data. These initial results show the effectiveness of incorporating 3D vision in radiological detection systems.
Abstract: Publication date: Available online 22 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Sohyeon Park, Geehyun Kim, Gyemin Lee A rotational modulation collimator (RMC) is an indirect imaging technique for locating remote radiation sources. However, when the counts of detected radiations are low, the RMC generates artifacts in the reconstructed images. To solve this problem, we propose a new reconstruction algorithm. Our algorithm removes noise in an RMC modulation pattern using a variance stabilization transformation and a non-local means filter. We verify that the proposed method enhances the performance of the reconstructed images through experiments with Monte Carlo simulation data.
Abstract: Publication date: Available online 12 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): J.D. Maxwell, J. Alessi, G. Atoian, E. Beebe, C.S. Epstein, R.G. Milner, M. Musgrave, A. Pikin, J. Ritter, A. Zelenski We report high steady-state nuclear polarization of 1 torr 3He gas nuclei via metastability exchange optical pumping at magnetic fields above 2 T. The introduction of highly polarized 3He gas into Brookhaven’s Electron Beam Ion Source would enable a new, polarized 3He ion source for use at the Relativistic Heavy Ion Collider and a future Electron–Ion Collider facility. By adapting recent developments in high field metastability exchange optical pumping for higher pressure gas, we have successfully polarized 1 torr 3He sealed cells in the EBIS solenoid. Through careful manipulation of the RF discharge parameters, polarizations above 80% were attained at 2, 3 and 4 T, with 89% being reached at 3 T with a 664 s relaxation time.
Abstract: Publication date: Available online 10 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): S. Gambetta, on behalf of the LHCb RICH collaboration The LHCb experiment has collected an unprecedented data sample to investigate beauty and charm hadrons decays. One of its key detector components is the RICH system providing excellent particle identification (PID) over a wide momentum range (2–100 GeV/c). Last year for the first time the RICH detectors have been operated in the automatic LHCb online alignment framework that, together with the well established calibration system, provided an excellent performance. The operations and performance of the RICH system during Run II are presented together with the activities performed during the winter shutdown to prepare for the last running period of the current RICH detectors before the LHCb upgrade.
Abstract: Publication date: Available online 10 February 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M.J. Joyce, R. Sarwar, V. Astromskas, A. Chebboubi, S. Croft, O. Litaize, R. Vogt, C.H. Zimmerman High-order angular correlations of fast neutrons emitted by spontaneous fission in californium-252 (252Cf) have been measured with a 2D array of 15 EJ-309 organic liquid scintillation detectors. These are compared with the results of Geant4 simulations using both an uncorrelated, average fission model and correlated fission models, which have also been used to quantify the impact of detector cross-talk on these distributions. In general, a bipolar trend is observed up to and including quadruple events, that is, θ12, θ13 and θ14. A bias as θ→0∘ in these data is observed that is consistent with the expectation of cross-talk being more prevalent for nearest-neighbour detectors. This is observed to be reduced for higher orders (θ13 and θ14 relative to θ12) and for wider gate widths (25 ns rather than 10 ns), consistent with this phenomenon being cross-talk. For the case of θ13, each of the composite angular distributions for the 14 detector positions 24∘≤θ≤336∘ have also been derived: a variation from a bipolar trend to a more isotropic behaviour, accompanied by a reduction in the relative level of response, is observed in these data for detector angles orthogonal to the reference detector at 0∘ consistent with the majority of neutrons being emitted from accelerated fragments. This research constitutes an important step towards quantifying and managing cross-talk as arrays of organic scintillators attract interest for practical applications such as nuclear materials assay.
Abstract: Publication date: Available online 19 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): H.L. Kim, J.A. Jeon, I. Kim, S.R. Kim, H.J. Kim, Y.H. Kim, D.H. Kwon, M.K. Lee, J.H. So We have developed a compact cryogenic measurement system to investigate the phonon and scintillation properties of various scintillating crystals. This system employs a 1 × 1× 1 cm3 crystal for the simultaneous detection of heat (phonon) and light (scintillation) signals based on metallic magnetic calorimeter (MMC) readouts at milliKelvin temperatures. Three molybdate crystals of CaMoO4, Na2Mo2O7, and Li2MoO4 were tested in the detector system. This work surveys scintillating crystals as target materials for neutrinoless double beta (0νββ) decay of 100Mo. All the measurements are successful in simultaneously detecting heat and light signals from the crystals. The measurements also results in clear particle identification using the pulse shapes and the relative amplitude ratios of the heat and light signals. We report the performance of the detector system through the amplitudes and time constants of the signals and the particle identification discrimination powers with discussion on 0νββ applications.
Abstract: Publication date: Available online 17 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): A. Jain, A. Chandra, S.R. Dugad, S.K. Gupta, B. Hariharan, P. Jagadeesan, P.K. Mohanty, S.D. Morris, P.K. Nayak, P.S. Rakshe, K. Ramesh, B.S. Rao, L.V. Reddy, M. Zuberi, Y. Hayashi, S. Kawakami, S. Ahmad, H. Kojima, A. Oshima, S. Shibata The Gamma Ray Astronomy at Pev EnergieS phase-3 (GRAPES-3) experiment, located at 11.4∘N latitude, 76.7∘E longitude and 2200 m altitude on the beautiful slopes of the Nilgiris hills at Ooty, India, consists of a world class indigenously developed detector system. The faithful operation and continuous improvement in the design of detectors, its associated electronics and the analysis software over a period of two decades has resulted in a better understanding of the universe at high energies. The GRAPES-3 is capable of studying the high energy cosmic ray composition in the knee region of the spectrum Gupta, (2005) solar flares, coronal mass ejection, and acceleration of particles in the atmospheric electric field. The core elements of the experiment are plastic scintillator (Sc) detectors and proportional counters (PRCs). The current status of the GRAPES-3 experimental system along with plans for the future upgrade are presented.
Abstract: Publication date: Available online 17 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Michael R. Abel, Linda H. Nie PurposeThe purpose of this study is twofold; first, a prompt gamma-ray neutron activation analysis (PGNAA) system will be constructed and employed in order to find the approximate sensitivity to elemental iron upon spectroscopic analysis. Concurrently, a Monte Carlo (MC) simulation model of the same PGNAA system will be defined such that the neutron source and resulting gamma-ray emissions are temporally collimated using the neutron associated particle (AP) technique. The experimental and simulated gamma-ray spectra may then be compared – taking into account the technological parameters and physical limitations of the PGNAA system – to determine how the sensitivity of the system may be improved due to photon signal discrimination inherent to the application of AP timing.MethodsThe presented PGNAA system utilized a deuterium-deuterium (DD) neutron generator with an isotropic flux on the order of 1E9/s and a 2” x 2” thallium-doped sodium iodide (NaI(Tl)) detector integrated with a Canberra Digital Spectrum Analyzer (DSA-1000). The accompanying MC model was defined in MCNP by an isotropic 2.5 MeV DD neutron source, iron as the target element, the components of the neutron generator, the supporting apparatus and shielding materials, and finally, by a volume of sodium iodide analogous to the experimental detector to serve as the spectroscopic focal point. The MCNP f8 pulse height tally – in combination with Gaussian energy broadening – was used to generate the simulated gamma-ray spectra, while collimation settings within MCNP enabled the simulation of time-filtered spectra with significant background reduction as would be possible upon employing the AP technique.ResultsThe experimental PGNAA system provided only macroscopic sensitivity to elemental iron, as confirmed by the unfiltered MCNP simulations. However, upon incorporation of AP collimation, the apparent iron sensitivity increased by a factor of nearly 8, with an accompanying increase in signal-to-noise ratio (SNR) of over 700% in the spectral region of interest. Even with modest detection capabilities in a rudimentary PGNAA system, AP coincident time gating allowed for a simulated lower limit of detection (LLD) for iron < 0.5 kg, a sensitivity which may be further improved by including multiple, larger gamma-ray detectors as a means to approach in vivo elemental concentrations which are important in medical diagnostics as distinctive markers of the development and progression of a variety of diseases.ConclusionsThe sensitivity to elements such as iron offered by AP-gated PGNAA lends itself to potential applications in material characterization in homeland security and most intriguingly, to noninvasive tissue analysis where elemental disease signatures may be defined and explored as a means to novel diagnostic and interventional pathways. Incorporation of associated particle imaging transducers and electronics in forthcoming sealed tube neutron generator designs will not only allow for the experimental determination of elemental detection limits on a case-by-case basis but the capability to spatially orient quantified elemental distributions in three dimensions. Though preliminary, the results of this study indicate the efficacy of AP collimation with regard to increasing SNR and provide an important basis for refining future PGNAA systems.
Abstract: Publication date: Available online 17 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Xiaochun Lai, Elena M. Zannoni, Jonathan George, Ling-Jian Meng We have reported the design of the MRC-SPECT-II system based on the inverted-compound-eye (ICE) gamma camera to offer a >1% detection efficiency while maintaining a sub-500μm imaging resolution (Lai and Meng, 2018). One of the key challenges of using the ICE camera for SPECT imaging is whether one could develop an accurate point response function (PRF), given its complex aperture design and low fractionation accuracy of 3D printing. In this work, we will discuss (I) a combined experimental and analytical approach for deriving the precise PRF, and (II) an experimental imaging study to demonstrate the feasibility of using the ICE-camera for acquiring high-quality SPECT images with a sub-500μm resolution. These studies would help to overcome one of the major hurdles for implement ICE-cameras for practical SPECT imaging.
Abstract: Publication date: Available online 17 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): I. Kishon, A. Kleinschmidt, V.A. Schanz, A. Tebartz, O. Noam, J.C. Fernandez, D.C. Gautier, R.P. Johnson, T. Shimada, G.A. Wurden, M. Roth, I. Pomerantz Great progress has been made in recent years in realizing compact, laser-based neutron generators. These devices, however, were inapplicable for conducting neutron absorption spectroscopy because of the electromagnetic noise produced by the interaction of a strong laser field with matter. To overcome this limitation, we developed a novel neutron time-of-flight detector, largely immune to electromagnetic noise. The detector is based on a plastic scintillator, only a few-millimeters in size, coupled with a silicon photo-multiplier by a long light-guiding fiber. Using this detector, we demonstrated for the first time laser-based fast neutron spectroscopy. This achievement paves the way to realizing compact neutron radiography systems for research, security, and commercial applications, and introduces new prospects for probing the temperature of matter under extreme conditions and for inertial confinement fusion diagnostics.
Abstract: Publication date: Available online 17 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Yu.A. Bashmakov The influence of the discovery of Cherenkov radiation on the development of modern physics is discussed.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): O. Kortner, S. Kortner, H. Kroha, S. Podkladkin, R. Richter The design of a muon detector and first-level muon trigger system for the FCC-hh baseline experiment is presented. The baseline FCC-hh detector configuration with a solenoid magnet system providing a field integral of 18 Tm over a wide pseudorapidity interval and a muon system around the solenoid and the calorimeter system is assumed. In order to identify muons with high momentum resolution one needs to measure the muon incidence angle at the entry point of the muon system with an angular resolution better than 100 μrad. This precision can be achieved with chambers with two quadruple layers which are separated by a 1.5 m thick spacer structure and contain 15 mm diameter aluminium drift tubes filled with Ar:CO(93:7) at 3 bars absolute pressure. Each drift-tube chamber is combined with a double layer of thin-gap RPC chambers which provide bunch crossing identification with better than 1 ns time resolution, muon trigger seeds, and coordinate measurement along the tubes.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Gabriella A. Carini, Grzegorz W. Deptuch, Farah Fahim, Łukasz A. Kadłubowski, Pamela Klabbers, Stefan Lauxtermann, Per-Olov Petterson, Tom Zimmerman New accelerator-based photon sources require pixel detectors with fast readout rate and large dynamic range. When the development is focused on detecting soft x-ray single photons then low noise is another competing requirement of the detector. FLORA, conceived to exploit the high repetition rate operation at LCLS-II with focus on soft X-rays, is being developed to address these needs. It targets single photon sensitivity at 250 eV, a dynamic range of 104 photons per pixel per frame, a continuous readout of more than 40k frames per second (kfps), and a pixel of 50 um × 50 um. We present and discuss technical choices and test results of the first prototypes.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): T. Alexopoulos, M. Bianco, M. Biglietti, C. Bini, M. Byszewski, G. Iakovidis, P. Iengo, M. Iodice, E. Karentzos, S. Leontsinis, K. Ntekas, F. Petrucci, G. Sekhniaidze, O. Sidiropoulou, M. Vanadia, J. Wotschack The ATLAS collaboration at the Large Hadron Collider at CERN has endorsed the resistive-strip micromegas technology for the high luminosity upgrade of the first muon station in the high-rapidity region, the so called “New Small Wheel” project. It requires detectors with a spatial resolution of ∼100μm, fully efficient up to a particle rate of ∼20kHz/cm2. In order to demonstrate that the resistive-strip micromegas technology fulfills these requirements, small resistive bulk micromegas have been studied with radioactive sources and with high energy beams. The micromegas chambers were operated with an Ar+7%CO2 gas mixture and read out using the APV25 chip. Results on the detection efficiency and the position resolution are presented for track impact angles from 0° to 40°. A position reconstruction method has been developed for inclined tracks, called the “micro-TPC method”. A description of the method along with performance studies is presented. In addition, the impact of the unavoidable presence of pillars and the relative alignment of readout and resistive strips on the micromegas performance has been quantified. In view of the fact that the micromegas detectors will also contribute to the trigger in ATLAS their time response has been studied.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Kyle B. Grammer, Franz X. Gallmeier, Erik B. Iverson Neutron beamlines frequently include moving components such as neutron choppers. These components are typically wheels that rotate about a fixed axis in order to preferentially transmit or absorb neutrons of the desired energies. Capabilities were developed and implemented into MCNPX to include materials and surfaces in motion. The Chopper Extension implements rotating surfaces and media in MCNPX in order to provide a direct way to include rotating components in models for background calculation purposes.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): G. Bencivenni, R. De Oliveira, G. Felici, M. Gatta, M. Giovannetti, G. Morello, A. Ochi, M. Poli Lener, E. Tskhadadze The μ-RWELL is a single-amplification stage resisitive MPGD. The amplification element, realized on a polyimide foil micro-patterned with a high density blind-holes (wells), is embedded through a thin resistive film, in the readout PCB. The introduction of the resistive layer affects the charge spread on the readout electrodes and suppresses the transition from streamer to spark giving the possibility to achieve large gains (>104). As a drawback the capability to stand high particle fluxes is reduced. In order to get rid of such a limitation different resistive layouts with prompt current evacuation schemes have been designed. In this work we present the study of the performance of the high rate layouts done at PSI, together with the measurement of the space resolution for orthogonal and inclined tracks performed at CERN.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Dong Zhao, Wenbao Jia, Daqian Hei, Can Cheng, Jiatong Li, Aiyun Sun, Yajun Tang, Haoyu Lei A new approach based on Prompt Gamma-ray Neutron Activation Analysis (PGNAA) was proposed for measuring neutron energy spectra. A system, which consisted of a high purity germanium (HPGe) detector and a multi-layer sample, was used to validate the method. The composite layers of the sample comprised of lead, polymethyl methacrylate, sodium chloride powder and borated polyethylene. Prompt gamma-rays emitted from Pb, H, O, C, Cl and B were selected to determine the incident neutron energy spectrum. The response function for the production of gamma rays from these elements by monoenergetic neutrons was obtained through Monte Carlo simulations. Then the neutron fields of Cf-252 neutron source and D-T neutron generator were investigated with this approach. With the measured prompt gamma-rays and the response matrix, the neutron spectra were obtained through the PSO algorithm. The unfolded results have a good agreement with the simulation spectrum.
Abstract: Publication date: Available online 16 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Yong Jiang, Jian Wu, Yanpeng Yin, Yi Lu, Kunlin Wu, Xiaoqiang Fan, Jiarong Lei We tested a layered structure of 10B4C on 6LiF (10B4C/6LiF) neutron converter for use with silicon neutron detectors. The combined layers effectively improve the efficiency of thermal-neutron detection over that of traditional single-layer converters. Silicon neutron detectors were constructed from a 2 cm × 2 cm silicon planar detector and coupled with removable neutron converters made from layers of 10B4C, 6LiF, or 10B4C/6LiF deposited on ceramics. The responses of these devices were tested with an 241Am–Li neutron source and the accompanying background gamma rays. The capability of the devices to discriminate neutron events from background gamma rays was tested by varying the bias voltages of the detectors when irradiated with an 241Am–Li neutron source and with 137Cs or 60Co gamma sources. The silicon neutron detector using the 10B4C/6LiF converter of 1.2-μm-thick 10B4C and 21.1-μm-thick 6LiF achieved the expected thermal-neutron detection efficiency of 5.6%. The compact size, simple construction, and low bias voltage of these devices make them promising for neutron detector applications like neutron dosimeters and beam monitors.
DOI capabilities, which can significantly improve the quality of PET images.
Abstract: Publication date: Available online 12 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Jitendra Kumar Mishra, B.V. Ramarao, Manjiri M. Pande, Gopal Joshi, Archana Sharma, Pitamber Singh The amplitude and phase variability among combiner inputs result in combining loss and degradation in amplifier’s combining efficiency. An analysis on combining efficiency is presented to understand the effect of variability in the combiner inputs and combiner transmission parameters. For symmetrical combiners, combining efficiency depends on the variance of its input voltages and intrinsic loss in combiner itself, whereas combining efficiency depends on mean of its inputs as well. Lower bound on combining efficiency has also been derived. The lower bound presented here offers an improvement over the lower bound reported in earlier works. Knowing the maximum spread in amplifier gain (magnitude and phase) in a production process, it is possible to predict the worst case combining efficiency. The derivations have been validated with the help of system simulation using measured results of power combiner.
Abstract: Publication date: Available online 12 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): H. Tsuchiya, M. Koizumi, F. Kitatani, H. Harada A large-volume (ϕ12.0 cm×12.7 cm) LaBr3 scintillation detector equipped with a specially-designed radiation shield was evaluated for neutron resonance capture analysis at the neutron time-of-flight (TOF) facility GELINA. By using the LaBr3 detector with and without the shield, measurements were carried out at a 13-m TOF station with three metallic samples, namely, Ni, Cr, and Fe. In addition, Monte Carlo simulations with Geant4 were performed, and the results were compared with the measurements to analyze the observed energy spectra and TOF spectra. Energy spectra obtained with the shield showed that prompt γ-ray peaks emitted from each sample can be used to identify the isotopes. Moreover, the signal-to-noise ratios of resonance peaks in a TOF spectrum with the shield were enhanced 1.5−2.5 in comparison with those without the shield. Furthermore, simultaneous measurements conducted using the three samples demonstrated that the shield employed herein was indispensable for identifying impurities in a composite sample such as particle-like fuel debris.
on assessment of uncertainties of cascade-related quantities” [Nucl.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): T. Hirade, H. Ando, K. Manabe, D. Ueda In this paper, we propose a detector identification method that uses waveform shape analysis. This method can be used in many experimental contexts involving detectors, leading to effective data acquisition. Detector identification can additionally be used for other critical tasks, such as determining detector position. In this study, we used the proposed detector identification method to perform positron annihilation age-momentum correlation measurements. Instead, of one detector, four scintillation detectors were used for detecting 1.275 keV gamma-rays from 22Na, a positron emitter. This method resulted in a fourfold higher count rate. Therefore small scintillators that are inevitable to have a low count rate could be also used for scintillation detectors to improve the time resolution, as a favourable time resolution such as 170 ps (full width at half maximum) is often required in research.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Siwei Xie, Xi Zhang, Hui Peng, Jingwu Yang, Qiu Huang, Jianfeng Xu, Qiyu Peng The signal-to-noise ratio (SNR) of the reconstructed image of Positron Emission Tomography (PET) can be improved by the timing measurement. In this article, we designed, fabricated and tested 32 time-of-flight (TOF) detectors for the second generation of Tachyon TOF-PET scanners. The detector module consists of two arrays of 2 × 12 lutetium-yttrium oxyorthosilicate (LYSO) crystal cubes of 6 ×6× 6 mm3. The discrete crystals were coupled to the 6 mm silicon photomultipliers (SiPMs) with optical glue. All the SiPM were tested for dark current. To correct the errors in the timing measurements caused by time-walk, two compensation methods (log-correction and linear-correction) based on the relationship between energy and timing information were purposed. As a comparison, the SiPM arrays coupled to 4 mm and 6 mm side crystal cube without optical glue were tested for coincidence timing resolution (CTR). The mean and standard deviations (SD) of dark current for the 1536 tested SiPMs were 12.72 +/- 1.70 μA at the bias voltage of 31.5 V and the temperature of 20 °C (±1 °C). CTR performance has increased by ∼5% within a narrow energy window, and ∼10% in a wide energy window by log-correction. The mean and SD of the CTR of 6 mm side crystal cube glue coupled was 126.9 +/- 3.6 ps for the 768 pairs of tested SiPMs. The detector is expected to provide a technical reference for the next generation of ultra-fast CTR commercial PET scanner using multilayer detectors.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): X. He, (eRD14 Collaboration) In the proposed Electron-Ion Collider (EIC) experiments, particle identification (PID) of the final state hadrons in semi-inclusive deep inelastic scattering allows the measurement of flavor-dependent gluon and quark distributions inside nucleons and nuclei. The EIC PID consortium (eRD14 Collaboration) has been formed for identifying and developing PID detectors using ring imaging Cherenkov (RICH) techniques for the future EIC experiments in a broad kinematic coverage. In this article, we summarize the recent work of the eRD14 Collaboration on three RICH detector systems: DIRC, dual radiator RICH, and compact modular RICH.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Camille Ducoin, Guillaume Maquart, Olivier Stézowski The level structure of nuclei offers a large amount and variety of information to improve our knowledge of the strong interaction and of mesoscopic quantum systems. Gamma-ray spectroscopy is a powerful tool to perform such studies: modern gamma-ray multi-detectors present increasing performances in terms of sensitivity and efficiency, allowing to extend ever more our ability to observe and characterize abundant nuclear states. For instance, the high-spin part of level schemes often reflects intriguing nuclear shape phenomena: this behaviour is unveiled by high-fold experimental data analysed through multi-coincidence spectra, in which long deexcitation cascades become observable. Determining the intensity of newly discovered transitions is important to characterize the nuclear structure and formation mechanism of the corresponding levels. However, it is not trivial to relate the apparent intensity observed in multi-gated spectra to the actual transition intensity. In this work, we introduce the basis of a formalism affiliated with graph theory: we have obtained analytic expressions from which data-analysis methods can eventually be derived to recover this link in a rigorous way.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M.P. Taggart, M. Nakhostin, P.J. Sellin In this work we investigate the potential use as a thermal neutron detector of cerium-doped gadolinium aluminium gallium garnet (GAGG:Ce) coupled to a silicon photomultiplier (SiPM). The response to thermal neutrons has been measured, with two strong low energy neutron-indicative peaks clearly identifiable below 100 keV and additional γ peaks at higher energies. The neutron-related peaks are produced by a combination of contributions from excited states of the two isotopes 156Gd and 158Gd which can be clearly resolved in our GAGG scintillation detector. In particular, two peaks due to neutron-induced γ-ray emission are observed at approximately 82 keV and 260 keV, with best achieved energy resolutions of 24.1 ± 0.2% and 22.7 ± 0.7% respectively. Three different scintillator volumes (0.1 cm3, 0.4 cm3, and 1 cm3) were investigated and the respective results for each configuration will be presented.Our findings show that a GAGG-SiPM based detector can be used as a compact, efficient thermal neutron detector in a low γ-ray contamination environment.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Stoeckl, A.A. Solodov Three x-ray spectrometers—the hard x-ray detector (HXRD), the bremsstrahlung MeV x-ray spectrometer (BMXS), and the hard x-ray image plate (HXIP)—are used to estimate hot-electron bremsstrahlung spectrum parameters for inertial confinement fusion experiments on OMEGA. Using 1-D deterministically calculated response functions, they show significantly different estimates of spectrum slope temperature. For all three detectors, 3-D Geant4 Monte Carlo simulations are developed and used to compute instrument response functions. Simulations explain features in raw image-plate data, but only significantly improve systematic errors in predicted detector channel signals for BMXS and do not entirely eliminate the discrepancy between estimates of slope temperature.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): G.L. Montagnani, L. Buonanno, D. Di Vita, M. Carminati, F. Camera, A. Gola, V. Regazzoni, C. Fiorini LaBr3:Ce crystals represent a key element for high-resolution gamma-ray detectors based on indirect conversion. Recent developments in crystal technologies have brought to the market Sr2+ co-doped 3″scintillators with a light yield 28% higher than standard LaBr3 crystals. Concurrently, high-density silicon photo-multipliers (SiPM) have enabled the possibility of solid-state readout of these crystals, providing state-of-the-art energy resolution and wide dynamic range. In order to assess the performance of a solid-state readout of a large LaBr crystal, we developed a low-noise readout instrument based on a 12 × 12 array of 6 mm × 6 mm NUV-HD SiPMs produced by FBK. The array of photo-detectors was coupled to a custom-developed 8-channel ASIC with automatic gain switching named GAMMA. Detector biasing, data acquisition, processing and transfer are performed by a compact microcontroller-based unit. The resulting instrument was tested with two different crystals: a standard 3″LaBr3:Ce3+ and the Sr2+ co-doped version. Thanks to the low-noise performance of SiPMs and of the electronics it has been possible to investigate the ultimate noise performance of the crystal and compare the results between the two crystals. A 3.4% FWHM energy resolution at the 137Cs 662 keV photopeak was measured with the standard LaBr3 crystal, while it decreased to 2.6% at 662 keV with the co-doped crystal. Beyond presenting the unprecedented spectroscopic performance of the co-doped crystal, this work is a further demonstration of the SiPM consolidating technology suitability to replace photo-multiplier tubes (PMT) for demanding applications in nuclear physics and astrophysics.
Abstract: Publication date: Available online 11 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): E. Currás, J. Duarte-Campderrós, M. Fernández, A. García, G. Gómez, J. González, R. Jaramillo, D. Moya, I. Vila, S. Hidalgo, M. Manna, G. Pellegrini, D. Quirion, D. Pitzl, A. Ebrahimi, T. Rohe, S. Wiederkehr A study of 3D pixel sensors of cell size 50μm×50μm fabricated at IMB-CNM using double-sided n-on-p 3D technology is presented. Sensors were bump-bonded to the ROC4SENS readout chip. For the first time in such a small-pitch hybrid assembly, the sensor response to ionizing radiation in a test beam of 5.6 GeV electrons was studied. Results for non-irradiated sensors are presented, including efficiency, charge sharing, signal-to-noise, and resolution for different incidence angles.
Abstract: Publication date: Available online 10 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): E. Bouquerel, E. Traykov, K.P. Nesteruk, S. Braccini, T.S. Carzaniga, C. Mathieu, M. Pellicioli, M. Rousseau, C. Ruescas, J. Schuler, S. Vichi The PRECy project foresees the use of a 16-25 MeV energy proton beam produced by the TR24 cyclotron, named CYRCé, recently installed at the Institut Pluridisciplinaire Hubert Curien (IPHC) in Strasbourg for research in radiation biology. One of the exit ports of the cyclotron will be used for this application along with a combination magnet. The platform will consist of up to 5 experimental stations linked to beamlines located in a dedicated area next to the cyclotron vault. One of the beamlines will receive proton beams of a few cm diameter at intensities up to 100 nA. In order to characterize the beam extracted from the cyclotron, the transverse beam emittance was studied by means of different methods.
Abstract: Publication date: Available online 10 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Oliver Kortner, on behalf of the ATLAS Collaboration The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC, where the instantaneous luminosity will exceed the LHC design luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the current system. This first level trigger limitation can be overcome by including data from the precision muon drift tube (MDT) chambers. This requires the fast continuous transfer of the MDT hits to the o -detector trigger logic and a fast track reconstruction algorithm performed in the trigger logic. The feasibility of this approach was studied with LHC collision data and simulated data. Two main options for the hardware implementation will be studied with demonstrators: an FPGA based option with an embedded ARM microprocessor and an associate memory chip base option. In this note the basic MDT trigger concept and the design of a demonstractor for the two hardware options are presented.
Abstract: Publication date: 1 July 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 931Author(s): V. Babiano, L. Caballero, D. Calvo, I. Ladarescu, P. Olleros, C. Domingo-Pardo We report on the spatial response characterization of large LaCl3(Ce) monolithic crystals optically coupled to 8 × 8 pixel silicon photomultiplier (SiPM) sensors. A systematic study has been carried out for 511 keV γ-rays using three different crystal thicknesses of 10 mm, 20 mm and 30 mm, all of them with planar geometry and a base size of 50 × 50 mm2. In this work we investigate and compare two different approaches for the determination of the main γ-ray hit location. On one hand, methods based on the fit of an analytical model for the scintillation light distribution provide the best results in terms of linearity and field of view, with spatial resolutions close to ∼1 mm fwhm. On the other hand, position reconstruction techniques based on neural networks provide similar linearity and field-of-view, becoming the attainable spatial resolution ∼3 mm fwhm. For the third space coordinate z or depth-of-interaction we have implemented an inverse linear calibration approach based on the cross-section of the measured scintillation-light distribution at a certain height. The detectors characterized in this work are intended for the development of so-called Total Energy Detectors with Compton imaging capability (i-TED), aimed at enhanced sensitivity and selectivity measurements of neutron capture cross sections via the time-of-flight (TOF) technique.
Abstract: Publication date: 1 July 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 931Author(s): G. Greaves, A.H. Mir, R.W. Harrison, M.A. Tunes, S.E. Donnelly, J.A. Hinks Radiation damage is a complex dynamic process with multiple atomic mechanisms interacting and competing to determine the end state of the material. Transmission electron microscopy (TEM) with in-situ ion irradiation allows direct observation of the microstructural evolution of a sample from the virgin to end state. A new TEM with in-situ ion irradiation has been established at the University of Huddersfield: the Microscope and Ion Accelerators for Materials Investigations (MIAMI-2) system. MIAMI-2 combines a 300 kV TEM with medium-energy 350 kV and low-energy 20 kV ion beamlines. Whilst the medium-energy beamline can be used for most species up to Au, the low-energy beamline is primarily designed for implanting light-ion species such as H and He. These can be used individually or mixed prior to entering the TEM allowing dual-ion-beam irradiation experiments to, for example, simulate the combined effects of displacement damage and the introduction of He from (n, α) nuclear reactions. The TEM can operate from 60–300 kV and is equipped with a 16 megapixel digital camera, an energy-filtered imaging system and an energy-dispersive X-ray spectrometer for elemental and chemical analysis. Sample temperature can be varied from –170 °C to 1300 °C and a gas injection system enables gaseous environments at pressures of up to 10−2 mbar at the sample position. The new MIAMI-2 system is a powerful tool for the investigation of radiation damage in a wide range of materials which are exposed to irradiating environments either during processing and/or whilst in-service in areas including nuclear applications, nanotechnology, semiconductor processing and extraterrestrial environments.
Abstract: Publication date: 1 July 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 931Author(s): Z. Fang, M. Sato, K. Futatsukawa, Y. Fukui, F. Naito, T. Sugimura, T. Obina, Y. Honda, F. Qiu, S. Michizono, S. Anami, H. Kobayashi, T. Kurihara, T. Miyajima, T. Ohba, N. Nagura An 8-MeV linear proton medical accelerator designed with a high RF duty operation is being developed at Ibaraki Neutron Medical Research Center for iBNCT (Ibaraki - Boron Neutron Capture Therapy). The reliability and stability of the cooling water control system has become one of the most important issues in realizing the medical application of the accelerator, which is designed considering high performance and low costs. However the previous cooling water control system with a commercial PID (Proportional–Integral–Differential) controller could not meet the operation requirements of the medical accelerator. Therefore, a new intelligent cooling water controller is successfully developed by application of Fast Feed-forward for Future (FFF). The detailed design of the intelligent cooling water control system and its great efficacy in improving accelerator operation is described in this paper. The stability of the cooling water temperature is improved greatly from the previous ±0.30°C to the current ±0.03°C. Moreover, the response time of cooling water control is decreased dramatically from the previous 5 min to approximately 20 s. Precise operation and an excellent auto-tuning of the RFQ (Radio Frequency Quadrupole LINAC) cavity are realized by using this stable and intelligent water control system. The beam transmittance is also improved slightly after a fine scan experiment with different settings of RF devices under stable acceleration operation. Finally, the RF startup time is also reduced by using this intelligent cooling water control system. Now the iBNCT accelerator operation is greatly improved with a very high reliability and stability. The accelerator will be operated as a practical medical therapy in late 2019. The technology developed in this intelligent cooling water control system will be very useful for the development of similar accelerators with high performance and low cost.
Abstract: Publication date: 1 July 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 931Author(s): Sunita Sahoo, Susnata Seth, Mala Das The bubble nucleation in superheated emulsion starts with the formation of critical sized vapour embryo in the liquid. The homogeneous nucleation can be triggered due to the energy deposition by the different kinds of radiations. At lower degree of superheat, higher ionizing particles can trigger the bubble formation. As the degree of superheat increases, lower ionizing particles also become responsible for bubble nucleation. In the present work, the bubble nucleation by the lower ionizing particles, e.g. gamma-rays has been discussed. Experiments were performed with R-134a (C2H2F4, b.p. -26.3 oC) superheated droplets in presence of 137Cs (662 keV, 5 mCi) gamma source. From the GEANT4.10.02 simulation, it is observed that near the threshold temperature of gamma-ray, stopping power of electron having energy corresponding to its highest value at the end of the track is mostly responsible for initiating a bubble nucleation, whereas with increase in temperature of the liquid, electrons of other energies could play role in the bubble nucleation process. The nucleation occurs due to the energy deposition by the produced electrons (secondary and higher order) at the end of their tracks within the liquid.
Abstract: Publication date: Available online 10 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Korzhik, K.-Th. Brinkmann, G. Dosovitskiy, V. Dormenev, A. Fedorov, D. Komar, V. Kozemiakin, D. Kozlov, V. Mechinsky, H.-G. Zaunick, I. Yashin, A. Iyudin, V. Bogomolov, S. Svertilov, I. Maximov High light yield scintillation materials on the base of lanthanide ions were demonstrated to be a multipurpose scintillation materials. They are widely used to detect γ–quanta and now become prospective to detect neutrons as well. Neutrons were detected through several distinct low energy γ–quanta peaks, generated by lanthanide nuclei in the materials under neutrons. Among three crystalline scintillators, namely lutetium oxy-orthosilicate, lanthanum bromide and gadolinium-aluminum-gallium garnet, the Gd3Al2Ga3O12:Ce (GAGG) scintillator showed the best performance and sensitivity due to the low internal background radioactivity and good cross section of neutron capture by natural mixture of the matrix host-creating Gd ions. The material fits the requirements for neutron detector properties – high Gd content and high scintillation light yield, stopping power and reasonable energy resolution for γ-quanta. These findings create prospects to construct compact multipurpose detectors for space and other application.
Abstract: Publication date: Available online 10 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Hengying Zhang, Yanhong Yu, Khuram Tariq, Zongkang Zeng, Xiurong Li, Cheng Liu, Dong Liu, Cunfeng Feng, LHAASO Collaboration In the Large High Altitude Air Shower Observatory (LHAASO), the main physics objective of the water Cherenkov detector array (WCDA) is to survey the sky for gamma-ray sources in the energy range of 100 GeV to 30 TeV. In order to extend the dynamic range of the WCDA, a 1.5-inch photomultiplier tube (PMT) is placed aside the 8-inch PMT in each cell of the WCDA. All of these 1.5-inch PMTs (900 in total) consist of the WCDA dynamic extended system (WCDA++). These PMTs are required to maintain linearity within four orders of magnitude. The performance of the 1.5-inch PMTs with a specially designed bi-readout voltage divider is tested with a PMT test system. Accordingly, the effects of the working high voltage and signal width on the dynamic range of the PMTs are studied. The test results show that the dynamic range with a 5% non-linearity for a driven signal width of 5.5 ns is more than 200 kPEs (photoelectrons). The dark noise count rate is less than 200 Hz for a 1 mV threshold at a PMT gain of 2×105. These results confirm that the PMT performance meets the WCDA++ requirements.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Tobias Flick, ATLAS Collaboration In the high-luminosity era of the Large Hadron Collider, the instantaneous luminosity is expected to reach unprecedented values, resulting in about 200 proton–proton interactions in a typical bunch crossing. To cope with the resulting increase in occupancy, bandwidth and radiation damage, the ATLAS Inner Detector will be replaced by an all-silicon system, the Inner Tracker (ITk). The innermost part of ITk will consist of a pixel detector, with an active area of about 14 m2. In order to cope with the changing requirements in terms of radiation hardness, power dissipation and production yield, several different silicon sensor technologies will be employed in the five barrel and end-cap layers. With the arrival of the first readout chip prototype, the RD53A chip, the development of hybrid detector modules is starting to address numerous production issues, understanding of which will be crucial for the final design and production of the ITk pixel detector modules. In addition, the new powering scheme is serial which introduces further challenges. A large prototyping program on system test level is ongoing. Components for larger structures with multiple modules, based on the FE-I4 front-end chip, which is currently used in the Pixel detector, were produced and are in assembly and evaluation. The paper will present the latest results from the assembly and characterization of prototype modules as well as the latest evaluation and results of thermo-mechanical prototypes and fully electrical prototypes.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M.J. Mallaburn, B.S. Nara Singh, D.M. Cullen, D. Hodge, M.J. Taylor, M.M. Giles, L. Barber, C.R. Niţă, R.E. Mihai, C. Mihai, R. Mărginean, N. Mărginean, C.R. Nobs, E.R. Gamba, A.M. Bruce, C. Scholey, P. Rahkila, P.T. Greenlees, H. Badran, T. Grahn Fast-timing measurements at the focal plane of a separator can suffer from poor timing resolution. This is due to the variations in time-of-flight (ToF) for photons travelling to a given detector, which arise from the changes in the implantation positions of the recoil nuclei emitting the γ rays of interest. In order to minimise these effects on timing measurements, a procedure is presented that improves fast-timing data by performing ToF corrections on an event-by-event basis. This method was used to correct data collected with an array of eight LaBr3 detectors, which detected γ rays from spatially distributed 138Gd recoil-implants at the focal plane of the Recoil-Ion-Transport-Unit (RITU) spectrometer. The Generalised Centroid Difference (GCD) method was used to extract a lifetime from data in conjunction with a new procedure to calibrate the time walk. The lifetime of the first 2+ state in 138Gd, populated by the decay of the Kπ=8− isomeric state, was measured to be 229(24) ps using the ToF-corrected data, which is consistent within three standard deviations to the literature value. The results together with Monte-Carlo simulations show that the ToF correction procedure reduced the uncertainty in the measured lifetimes by 3 % in the case of the spatially distributed nuclei at the focal plane of RITU. However, ∼12 % has been estimated for a similar experiment when using a larger focal plane i.e. the Super-FRS at the FAIR facility.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): R. Guida, B. Mandelli, G. Rigoletti Resistive Plate Chamber (RPC) detectors are widely used at the CERN LHC experiments as muon trigger thanks to their excellent time resolution. They are operated with a Freon-based gas mixture containing C2H2F4 and SF6, both greenhouse gases (GHG) with a very high global warming potential (GWP). The search of new environmentally friendly gas mixtures is necessary to reduce GHG emissions and costs as well as to optimize RPC performance. Several recently available gases with low GWP have been identified as possible replacements for C2H2F4 and SF6. More than 60 environmentally friendly gas mixtures have been investigated on 2 mm single-gap RPCs. The RPC detectors have been tested in laboratory conditions and at the CERN Gamma Irradiation Facility (GIF++), which provides a high energy muon beam combined with an intense gamma source allowing to simulate the background expected at HL-LHC. The performance of RPCs were studied at different gamma rates with the new environmentally friendly gases by measuring efficiency, streamer probability, rate capability, induced charge, cluster size and time resolution. To finalize the studies, the RPCs are now operated under gas recirculation with the selected new gas mixture and exposed to the intense gamma radiation of GIF++ for evaluating possible long-term aging effects, gas damage due to radiation and compatibility of LHC gas system with new gases.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Riham Mariam, Matias Rodrigues, Martin Loidl Emissions of L-X-rays by actinides are quite intense due to the large internal conversion coefficients of the gamma transitions. These emissions can be beneficial for the quantitative analysis of actinides by photon spectrometry, however the L X-rays emitted by radionuclides are generally not well known. Several studies explored the L-X-ray regions of actinides and measured total intensities of L-X-ray groups, partially with large uncertainties up to 10 %. However, they cannot resolve the individual L-X-ray lines due to the limited energy resolution (of the order of 200 eV (FWHM) at 25 keV) of the semi-conductor detectors. The present work shows and discusses the measurement of individual L-X-ray line emission intensities emitted by Cm-244 using an ultra-high-resolution spectrometer. The used spectrometer is a Metallic Magnetic Calorimeter (MMC) conceived for photon spectrometry below 100 keV with an energy resolution of 37 eV at 20 keV and a nearly constant efficiency over the L X-ray energy range. A high-resolution spectrum with a counting statistics of 4.6 × 106 counts was obtained. The spectrum processing allowed to determine the individual emission intensities of 30 L-X-ray lines despite the narrow energy spacing.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Kamil Brylew, Pawel Sibczynski, Marek Moszynski, Winicjusz Drozdowski, Jaroslaw Kisielewski Praseodymium activated lutetium aluminum garnet (LuAG:Pr) is an inorganic scintillator belonging to the garnet family of crystals. It is characterized by an emission related to the radiative and allowed 5d14f1→4f2 transition in trivalent praseodymium ions. It has been shown that it has good scintillation qualities such as light output, energy resolution and fast decay times.There have been attempts to enhance the already good properties of LuAG:Pr such as optimizing annealing conditions, since this material has a potential to be used in Positron Emission Tomography (PET) detector systems.Previously reported studies show that there have been successful cases of improving the light yield and energy resolution. In this paper we show a detailed study of the non-proportionality and energy resolution in LuAG:Pr crystals that have been modified by partially substituting lutetium with yttrium and introducing intentional trace amounts of molybdenum co-doping.The measurements have been performed with varied shaping times to study the influence of long decay components on the scintillation parameters.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): N. Alipour Tehrani, M. Benoit, M. Buckland, D. Dannheim, A. Fiergolski, S. Green, D. Hynds, I. Kremastiotis, S. Kulis, M. Munker, A. Nürnberg, I. Perić, M. Petrič, E. Sicking, M. Vicente In order to achieve the challenging requirements on the CLIC vertex detector, a range of technology options have been considered in recent years. One prominent idea is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel readout chips. Recent results have shown the approach to be feasible, though more detailed studies of the performance of such devices, including simulation, are required. The CLICdp collaboration has developed a number of ASICs as part of its vertex detector R&D programme, and here we present results on the performance of a CCPDv3 active sensor glued to a CLICpix readout chip. Charge collection characteristics and tracking performance have been measured over the full expected angular range of incident particles using 120 GeV/c secondary hadron beams from the CERN SPS. Single hit efficiencies have been observed above 99% in the full range of track incidence angles, down to shallow angles. The single hit resolution has also been observed to be stable over this range, with a resolution around 6 µm. The measured charge collection characteristics have been compared to simulations carried out using the Sentaurus TCAD finite-element simulation package combined with circuit simulations and parametrisations of the readout chip response. The simulations have also been successfully used to reproduce electric fields, depletion depths and the current–voltage characteristics of the device, and have been further used to make predictions about future device designs.
Abstract: Publication date: Available online 9 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): S.V. Chekanov We propose a method to organize experimental data from particle collision experiments in a general format which can enable a simple visualisation and effective classification of collision data using machine learning techniques. The method is based on sparse fixed-size matrices with single- and two-particle variables containing information on identified particles and jets. We illustrate this method using an example of searches for new physics at the LHC experiments.
Abstract: Publication date: Available online 8 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): B. Williams, Y.F. Zhu, Z. He Semiconductor detectors with pixelated anodes offer a desirable combination of position sensitivity and energy resolution that are suitable for numerous applications in gamma-ray detection and imaging. Pixelization of electrodes also entails a non-uniform amplitude response as a function of gamma-ray interaction position. Energy calibrations as a function of interaction position improve energy resolution, but systematic errors in the energy reconstruction process persist and limit energy resolution at fixed electronic noise.Digitization of signals induced on collecting and adjacent electrodes offers rich information about gamma-ray interactions and their charge drift and collection as a function of time. Despite the abundance of signals for each interaction, human intuition and rule-based approaches fail to utilize the entire set of observed signals to mitigate the sources of systematic error. In order to maximize the utility of digitized signals and improve energy resolution, principal component analysis is applied towards digitized signals observed in semiconductor detectors with pixelated anodes. Principal components identified in the process form the basis for position-specific energy corrections. By leveraging this additional information encoded within digitized signals, energy resolution improves by factors between 10 and 15% with respect to full-width at half and tenth maximum values. The feature that accounts for the maximum amount of explained variance between interactions in any given pixel correlates strongly with the depth of interaction.
Abstract: Publication date: Available online 8 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Erik Butz, for the CMS Tracker Group The era of High-Luminosity Large Hadron Collider will pose unprecedented challenges for detector design and operation. The planned luminosity of the upgraded machine is 5–7.5×1034cm−2s−1, reaching an integrated luminosity of 3000–4000 fb−1 by the end of 2039. The CMS Tracker detector will have to be replaced in order to fully exploit the delivered luminosity and cope with the demanding operating conditions. The new detector will provide robust tracking as well as input for the first level trigger. This report is focusing on the replacement of the CMS Outer Tracker system, describing new layout and technological choices together with some highlights of research and development activities.
Abstract: Publication date: Available online 8 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Osipenko, V. Ceriale, G. Gariano, M. Girolami, S. Cerchi, R. Nolte, E. Pirovano, M. Ripani, D.M. Trucchi In the present article we describe calibration measurements of the compact neutron spectrometer at the PTB quasi-monoenergetic neutron reference fields. The spectrometer is based on two diamond detectors enclosing a 6Li neutron converter. The conversion occurs through the 6Li(n,t)4He reaction, featuring the Q-value of 4.8 MeV. The incident neutron energy is measured through the sum of energies of the two conversion reaction products: t and α. The prototype used in this work was based on two 4 × 4 mm2 100μm thick single crystal CVD commercial diamond plates. The measurements were performed in the fission spectrum domain at five different neutron energies varying from 0.3 up to 2 MeV. The obtained data showed a very good neutron energy reconstruction, i.e. in agreement with its reference values within statistical uncertainties or with absolute deviations below 11 keV. The energy resolution of the spectrometer was found to be about 100 keV (RMS) with a small (about 9 keV/MeV) rising trend towards higher energies. The measured detection efficiency was found to be compatible with predictions based on analytical calculations and on Geant4 simulations within 3% statistical and 4% systematic uncertainty.
Abstract: Publication date: Available online 7 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Antonello, M. Caccia, R. Ferrari, S. Franchino, G. Gaudio, J. Hauptman, S. Lee, L. Pezzotti, R. Santoro, I. Vivarelli, R. Wigmans, on behalf of the INFN RD-FA Collaboration Future circular electron-positron colliders operating at s=90, 160, 240 and 350 GeV as Z, W, H and t factories will demand experiments with superior momentum and energy resolution for all the possible final-state particles produced. The IDEA Detector aims at satisfying these requests by exploiting an ultra-light drift chamber as the largest central tracker and a dual-readout fiber calorimeter for both electromagnetic and hadronic energy measurements. In this paper I review the dual-readout calorimeter baseline choices, as well as the related R&D work.
Abstract: Publication date: Available online 5 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): T.H. Hancock, S. Bhasin, T. Blake, N. Brook, T. Conneely, D. Cussans, C. Frei, R. Forty, E.P.M. Gabriel, R. Gao, T. Gershon, T. Gys, T. Hadavizadeh, N. Harnew, M. Kreps, J. Milnes, D. Piedigrossi, J. Rademacker, M. van Dijk The TORCH time-of-flight detector is designed to provide particle identification in the momentum range 2−10GeV∕c over large areas. The detector exploits prompt Cherenkov light produced by charged particles traversing a 10mm thick quartz plate. The photons propagate via total internal reflection and are focused onto a detector plane comprising position-sensitive Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMT) detectors. The goal is to achieve a single-photon timing resolution of 70ps, giving a timing precision of 15ps per charged particle by combining the information from around 30 detected photons. The MCP-PMT detectors have been developed with a commercial partner (Photek Ltd, UK), leading to the delivery of a square tube of active area 53×53mm2 with a granularity of 8×128pixels equivalent. A large-scale demonstrator of TORCH, having a quartz plate of dimensions 660×1250×10mm3 and read out by a pair of MCP-PMTs with custom readout electronics, has been verified in a test beam campaign at the CERN PS. Preliminary results indicate that the required performance is close to being achieved. The anticipated performance of a full-scale TORCH detector at the LHCb experiment is presented.
Abstract: Publication date: Available online 5 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Xin-Liang Yan, Rui-Jiu Chen, Meng Wang, You-Jin Yuan, Jian-Dong Yuan, Shao-Ming Wang, Guo-Zhu Cai, Min Zhang, Zi-Wei Lu, Chao-Yi Fu, Xu Zhou, Dong-Mei Zhao, Yuri A. Litvinov, Yu-Hu Zhang The Isochronous Mass Spectrometry (IMS) is a powerful tool for mass measurements of exotic nuclei with half-lives as short as several tens of micro-seconds in storage rings. In order to improve the mass resolving power while preserving the acceptance of the storage ring, the IMS with two Time-Of-Flight (TOF) detectors has been implemented at the storage ring CSRe in Lanzhou, China. Additional velocity information beside the revolution time in the ring can be obtained for each of the stored ions by using the double TOF detector system. In this paper, we introduced a new method of using a 658 nm laser range finder and a short-pulsed ultra-violet laser to directly measure the distance and time delay difference between the two TOF detectors which were installed inside the 10−11 mbar vacuum chambers. The results showed that the distance between the two ultra-thin carbon foils of the two TOF detectors was ranging from 18032.5 mm to 18035.0 mm over a measurable area of 20×20 mm2. Given the measured distance, the time delay difference which comes with signal cable length difference between the two TOF detectors was measured to be Δtdelay1−2=99(26) ps. The new method has enabled us to use the speed of light in vacuum to calibrate the velocity of stored ions in the ring. The velocity resolution of the current double TOF detector system at CSRe was deduced to be σ(v)∕v=4.4×10−4 for laser light, mainly limited by the time resolution of the TOF detectors.
Abstract: Publication date: Available online 5 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Sébastien Chabod In this study, we describe a procedure of topology optimization in the framework of the linear Boltzmann equation, implemented using the reference Monte-Carlo particle transport code MCNP. This procedure can design complex structures that optimize the transport of particles, according to preset objectives and constraints. Although simple and perfectible, this procedure has been successfully tested on a series of difficult problems, with results outperforming human capabilities. Improved, it could be used to assist or automate the design of particle optics or nuclear devices.
Abstract: Publication date: Available online 4 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): C.B. Hoshor, J.E. Currie, W.H. Miller, S.L. Bellinger, D.S. McGregor, A.N. Caruso Hand-held instrumentation that can provide real-time information regarding the location and identity (i.e., type/radioisotope and local surrounding/shielding) of neutron radiation sources, via free neutron measurements alone, are of interest to non-proliferation, water/oil-exploration and related neutron scattering applications. In a previous report, template-matching techniques in two- and three-spatial dimensions were introduced as methods for simultaneously determining the horizontal-planar location and the identity of neutron radiation sources with a new class of volumetrically-sensitive moderating-type neutron spectrometer. Although these methods were shown to be quite promising for this new class of instrumentation, there are three significant factors that negatively affect their performance in practice: (1) there are a large number of templates of interest for most practical applications; (2) many of these templates are very similar (i.e., highly correlated or strongly degenerate); and, (3) the measurement data is superposed with environmental neutron scattering effects. In this work, kernel Hilbert space transformations, that have been proposed to solve analogous problems in digital image processing applications, are employed to overcome the aforementioned difficulties encountered when analyzing spectroscopic neutron radiation measurements via template-matching techniques, and a novel kernel Hilbert space template-matching algorithm is introduced. Four variants of this improved technique are tested and compared via MCNP6 simulation for efficacy of localization and identification of neutron radiation sources with this new class of neutron spectrometer.
Abstract: Publication date: Available online 4 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): C.G. Pang, P. Bambade, S. Di Carlo, Y. Funakoshi, D. Jehanno, V. Kubytskyi, M. Masuzawa, Y. Peinaud, C. Rimbault, S. Uehara A fast luminosity monitor measuring the rate of the radiative Bhabha process at zero degree photon scattering angle based on diamond detectors was developed and successfully operated during the Phase-2 commissioning of SuperKEKB. The main purpose of this system, called LumiBelle2 is to provide: train integrated luminosity signals at 1 kHz with a relative precision better than 1% for luminosities higher than 1034 cm−2s−1, input to a dithering feedback system designed to maintain an optimum horizontal overlap between the two colliding beams at the Interaction Point (IP), and bunch integrated luminosity signals at 1 Hz which are useful for machine tuning and beam parameters studies of the successive bunches along the train. In this paper, design of the LumiBelle2 and Phase-2 results will be reported, including the evaluation of the single beam background, relative luminosity measurements, vertical beam size determinations at the IP using vertical offset scans.
Abstract: Publication date: Available online 4 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): N. van der Kolk, for the ALICE-FoCal Collaboration This contribution discusses the recent progress in the development of a highly granular digital electromagnetic calorimeter proposed as an upgrade to the ALICE detector. This forward electromagnetic calorimeter (FoCal) must be able to discriminate decay photons from direct photons at very high energy, which requires extremely high granularity and a small Molière radius. A dedicated R&D program is ongoing to develop the technology needed for such a high-granularity device. Within this program we have constructed a prototype of a digital electromagnetic calorimeter based on CMOS monolithic active pixel sensors (MAPS). This prototype has demonstrated the unique capabilities of such a highly granular digital calorimeter, providing unprecedented shower profile measurements and good linearity and energy resolution. The prototype was based on the MIMOSA chip, which is however not fast enough for application in a full detector at the LHC. As a next step, the ALPIDE chip developed for the ALICE Inner Tracker Upgrade is being investigated for performance with high occupancy. This contribution presents results from the current prototype, the performance of the ALPIDE and plans for the next prototype.
Abstract: Publication date: Available online 4 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Robert Münzer, for the ALICE Collaboration The Time Projection Chamber (TPC) of the ALICE experiment is being upgraded with new readout chambers based on Gas Electron Multiplier (GEM) technology during the second long shutdown of the CERN Large Hadron Collider. The upgraded detector will operate continuously and trigger-less without the use of a gating grid. It will thus be able to read out all minimum bias Pb-Pb events that the LHC will deliver at the anticipated peak interaction rate of 50 kHz for the high-luminosity heavy-ion era. After several years of R&D, the last two years were devoted to the production of 80 quadruple GEM chambers in several institutes and countries utilizing 640 GEM foils. The chambers underwent a detailed quality control procedure in order to ensure the highest standard as required for the installation in the ALICE TPC. To guarantee optimal operational safety, a careful design of the HV configuration, employing so-called cascaded power supplies, was developed. Continuous readout of the TPC data with rates of 3.28 TByte/s into the online data farm will be accomplished by a new TPC front-end scheme, utilizing the newly developed SAMPA readout ASIC and the GBT readout system developed at CERN.
Abstract: Publication date: Available online 3 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): E.J. Kluge, C. Stieghorst, Zs. Révay, P. Kudějová, J. Jolie The Prompt Gamma-ray Activation Imaging and Neutron Tomography (PGAI-NT) instrument at the PGAA facility of the Heinz Maier-Leibnitz Center (MLZ), provides a method to obtain and effectively visualize position-sensitive element abundances in samples by combining a three-dimensional extension of Prompt Gamma-ray Activation Analysis (PGAA) and Neutron Tomography (NT). Inspired by a proof-of-principle study, a cone-beam tomography set-up was designed, tested and installed.This article reports on the design of the new cone-beam tomography set-up and its optimization using neutron beam simulations and physical measurements. A new position-sensitive neutron detector with improved performance and instrument environment integration was designed, built and tested. The overall NT performance of the set-up is investigated in the course of a Quality Assessment for neutron tomography sites. Its stand-alone NT and all-in-one PGAI-NT suitability is determined.
Abstract: Publication date: Available online 3 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): P. Cenci, G. Anzivino, D. Aisa, M. Barbanera, M. Bizzarri, A. Bizzeti, F. Brizioli, F. Bucci, C. Campeggi, V. Carassiti, A. Cassese, R. Ciaranfi, V. Duk, E. Iacopini, J. Engelfried, N. Estrada-Tristan, E. Imbergamo, G. Latino, M. Lenti, R. Lollini The Ring Imaging Cherenkov detector of the NA62 experiment at the CERN SPS is a key element of particle identification in the NA62 experimental strategy. The detector fulfils different conditions: to distinguish pions from muons with a muon rejection factor of O(102) in the NA62 momentum range of operation, between 15 and 35 GeV/c; to measure particle arrival time in the decay region with a precision better than 100 ps; to provide fast signals and reference time to the NA62 trigger system. The main design aspects and functional characteristics, as well as the performance of the detector measured with the data taken in the first NA62 physics runs, will be summarized in this paper.
Abstract: Publication date: Available online 3 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): John Stakely Keller, ATLAS Collaboration The ATLAS experiment at the Large Hadron Collider is currently preparing major detector upgrades to meet the requirements of the High Luminosity LHC (HL-LHC), scheduled to begin in 2026. With the radiation damage and high density of tracks expected at the HL-LHC, the current Inner Detector would be inoperable, and will instead be replaced by an all-silicon Inner Tracker (ITk). The ITk consists of two sub-systems: a pixel detector close to the beam pipe, and a strip detector at larger radii. This paper presents results from an extensive design and prototyping effort for the ITk strip detector, including studies of the sensors, electronics, and support structures. The performance of the detector has been validated through testbeams, simulations, and thermal and electrical prototypes. Plans for the forthcoming production phase are also presented.
Abstract: Publication date: Available online 1 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): F. Dachs, J. Alozy, N. Belyaev, B.L. Bergmann, M. van Beuzekom, T.R.V. Billoud, P. Burian, P. Broulim, M. Campbell, G. Chelkov, M. Cherry, S. Doronin, K. Filippov, P. Fusco, F. Gargano, B. van der Heijden, E.H.M. Heijne, S. Konovalov, X. Llopart Cudie, F. Loparco Growing energies of particles at modern or planned particle accelerator experiments as well as cosmic ray experiments require particle identification at gamma-factors (gamma) of up to ∼ 105. At present there are no detectors capable of identifying charged particles with reliable efficiency in this range of gamma. New developments in high granular pixel detectors allow one to perform simultaneous measurements of the energies and the emission angles of generated transition radiation (TR) X-rays and use the maximum available information to identify particles. First results of studies of TR energy-angular distributions using gallium arsenide (GaAs) sensors bonded to Timepix3 chips are presented. The results are compared with those obtained using a silicon (Si) sensor of the same thickness of 500μ m. The analysis techniques used for these experiments are discussed.
Abstract: Publication date: Available online 1 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): D. Munteanu, S. Moindjie, J.L. Autran In this work, a water tank muon spectrometer was designed, assembled and operated to measure the energy distribution of low energy atmospheric muon flux induced by cosmic-rays at sea level in the energy range 100-500 MeV. The principle of this experiment is to use water as muon moderator inserted between two coincidence detectors to select the cutoff energy below which muons can no longer be detected. The differential and integral muon spectra are then derived from successive measurements by varying the liquid height within the water tank. The instrument was entirely characterized and modeled in terms of detector efficiency, cutoff energy and counting rate. Experimental data are reported for the energy distribution of muon flux at sea level (43∘N of latitude) and finally compared with literature survey.
Abstract: Publication date: Available online 1 April 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): M. Machida, D. Nishimura, M. Fukuda, S. Yagi, T. Sugihara, S. Kanbe, S. Yamaoka, M. Takechi, M. Tanaka, M. Amano, J. Chiba, K. Chikaato, H. Du, S. Fukuda, A. Homma, T. Hori, A. Ikeda, R. Ishii, T. Izumikawa, Y. Kamisho RI-RICH, a ring-imaging Cherenkov counter for radioactive ions, has been developed to measure the velocity of the ions at intermediate energies. Our RI-RICH system consists of six multi-anode photomultiplier tubes covered with 360-nm bandpass filters and a radiator made of quartz or BK7. For the primary 132Xe beam with a velocity of β=0.712, a velocity resolution of Δβ∕β=4.9×10−4 (one standard deviation σ) and a detection efficiency of more than 99.99% were achieved. For the secondary beams with Z=44–55 and β≃0.70, we successfully performed particle identification using the Bρ-ΔE-β method. The velocity resolutions of RI-RICH for these nuclides were equivalent to a more than 6σ separation for the mass number.
Abstract: Publication date: Available online 29 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): A. Amorese, C. Langini, G. Dellea, K. Kummer, N.B. Brookes, L. Braicovich, G. Ghiringhelli In many back-illuminated Charge Coupled Device (CCD) detectors the electrons liberated by the absorption of one X-ray photon quickly spread and generate charge-spots larger than the pixel dimensions. Such detectors are considered here. In the soft X-ray range this phenomenon drastically limits the effective spatial resolution to approximately 25 μm, irrespective of the pixel’s lateral size. For very low flux the charge-cloud centroid determination can be used, on each individual spot, to estimate the actual photon impact position with sub-pixel precision. The readout noise and speed, together with the charge and spatial undersampling, are the main factors limiting the accuracy of this procedure in commercial devices. We have experimentally measured a position uncertainty better than 7 μm and 10 μm for 13.5 μm and 20.0 μm pixel sizes respectively, around 1 keV photon energy using centroiding algorithms. This study was motivated by the need of high resolution detectors in resonant inelastic (soft) X-ray scattering (RIXS).
Abstract: Publication date: Available online 29 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Lukas Gruber, LHCb SciFi Tracker Collaboration LHCb will undergo a major upgrade during the LHC long shutdown 2 in 2019/2020 to cope with increased instantaneous luminosities and to implement a trigger-less 40 MHz readout. The current inner and outer tracking detectors will be replaced by a single homogeneous detector based on plastic scintillating fibres (SciFi). The SciFi tracker covers an area of 340 m2 by using more than 10,000 km of scintillating fibre with 250μm diameter, enabling a spatial resolution of better than 100μm for charged particles. Linear arrays of Silicon Photomultipliers cooled to -40°C are placed at the fibre ends. The readout of 524 k channels occurs through custom-designed front-end electronics. The assembly of the detector has started and the project is on track for installation starting end 2019. In view of future upgrades, a R&D program aiming at the development of very fast and efficient scintillating fibres, based on a novel type of luminophores (NOL), has been launched in parallel to the SciFi production. The performance of the prototype NOL fibres is competitive, in particular the decay time constant is close to 1 ns, i.e. about 50% shorter than the best standard fibre.
Abstract: Publication date: Available online 26 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Mark M. Bourne, Samuel G. DeBruin, Roy Clarke Silicon photomultiplier (SiPM) technology, when combined with fast timing detectors and electronics, can be used to design a compact time-of-flight neutron spectrometer capable of identifying correlated neutron sources such as spontaneous fission from plutonium. Two EJ-200 organic plastic scintillators were coupled to separate C-series SiPM arrays designed by Endectra and manufactured by SensL. These assemblies were placed 30 centimeters away from each other with a 252Cf source next to one detector. The time-of-flight distribution was used to compute the measured neutron energy distribution, whose shape compared favorably to the expected neutron energy distribution for neutron energies greater than 2 MeV.
Abstract: Publication date: Available online 20 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Alexei V. Smirnov Radio frequency (RF) and microwave power amplifiers using divider-combiner architecture are important blocks of rapidly developing middle and high power RF and microwave systems used in radars, communication, directed energy, electronic warfare, air traffic control, and scientific facilities such as particle accelerators. Many of these amplifiers need to operate in a wide dynamic range of output power levels. For conventional amplifiers that significantly reduces actual efficiency compared to the maximum efficiency attainable at maximum output power levels. Efficiency of a high power amplifier system can be made close to efficiency of a single amplifying module at compression if graceful degradation performance is dramatically improved. The approach is based on dynamic switching on and off some of the amplifying modules, and switchable termination of the corresponding ports of a reactive combiner with externally controlled phasing. The power-scalable method is validated with simulations demonstrating capability of power dynamic range exceeding 13 dB at nearly saturated efficiency of the active power modules and low insertion loss imposed by the passive RF components.
Abstract: Publication date: Available online 19 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): C.-A. Reidel, Ch. Finck, C. Schuy, M. Rovituso, U. Weber In ion-beam therapy, the elastic and inelastic interactions of the primary beam interacting with different mediums are of strong interest. Cross section and scattering measurements are important in order to provide accurate basic data for the treatment planning system. Using several planes of a high spatial resolution vertex detector based on monolithic CMOS pixel sensor technology is a common concept for measuring precise trajectories of charged particles before and after interactions. To reach high spatial resolution, the alignment of the sensors is mandatory. In this work, an alignment procedure based on a global χ2 cost function, that simultaneously optimizes the alignment parameters for all events is presented and shows accurate results which allow the detectors to reach high spatial resolution. The procedure was benchmarked with simulated and experimental data for the Mimosa28 pixel detector and compared to a state of the art alignment algorithm. The results of the alignment were in agreement with the requirements needed for precise measurements in particle therapy. The spatial resolution reached after the alignment was better than 10μm.
Abstract: Publication date: Available online 15 March 2019Source: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentAuthor(s): Bo Zhao, Tieming Zhu, Fengfeng Wang, Xiaofeng Jin, Chenxing Li, Wei Ma, Shuping Chen, Xinlong Zhu, Bin Zhang The thermal stability of the radio frequency quadrupole (RFQ) is an important concern during commissioning. The cooling water takes away the power dissipated on the RFQ internal surface to maintain the thermal stability and limit the structural deformation. In this paper, the thermal-fluid coupled analysis of the RFQ is described and 3D temperature distribution of the RFQ cavity structure is given. The method of adjusting the water temperature is determined through analysis. The heat transfer coefficient for the cooling channels and the outlet water temperature about the water cooling system are obtained. A comparison of the results in simulation and experiment is presented. The cooling system can meet the requirements of RFQ operating.

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