149 research outputs found
Mirror system of the RICH detector of the NA62 experiment
No full textA large RICH detector is used in NA62 to suppress the muon contamination in the charged pion selection by a factor 100 in the momentum range between 15 and 35 GeV/c. The detector consists of a 17 m long tank (vessel), filled with neon gas at atmospheric pressure. Cherenkov light is reflected by a mosaic of 20 spherical mirrors with 17 m focal length, placed at the downstream end, and collected by 1952 photomultipliers (PMTs) placed at the upstream end. In this paper the characterization of the mirrors before installation and the mirror support system are described. The mirror installation procedure and the laser alignment are also illustrated
Demonstration of Gd-GEM detector design for neutron macromolecular crystallography applications
No full textThe European Spallation Source (ESS) in Lund, Sweden will become the world's
most powerful thermal neutron source. The Macromolecular Diffractometer (NMX)
at the ESS requires three 51.2 x 51.2~cm detectors with reasonable
detection efficiency, sub-mm spatial resolution, a narrow point spread function
(PSF) and good time resolution. This work presents measurements with the
improved version of the NMX detector prototype consisting of a Triple-GEM
detector with natural Gd converter and a low material budget readout. The
detector was successfully tested at the neutron reactor of the Budapest Neutron
Centre (BNC) and at the D16 instrument at the Institut Laue-Langevin (ILL) in
Grenoble. The measurements with Cadmium and Gadolinium masks in Budapest
demonstrate that the point spread function of the detector lacks long tails
that could impede the measurement of diffraction spot intensities. On the D16
instrument at ILL, diffraction spots from Triose phosphate isomerase w/
2-phosphoglycolate (PGA) inhibitor were measured both in the D16 Helium-3
detector and the Gd-GEM. The comparison between the two detectors show a
similar point spread function in both detectors, and the expected efficiency
ratio compared to the Helium-3 detector. Both measurements together thus give
good indications that the Gd-GEM detector fits the requirements for the NMX
instrument at ESS
The TOTEM GEM telescope (T2) at the LHC
No full textThe TOTEM T2 telescope will measure inelastically produced charged particles in the forward region of the LHC Interaction Point 5. Each arm of the telescope consists in a set of 20 triple-GEM (Gas Electron Multiplier) detectors with tracking and t rigger capabilities. The GEM technology has been considered for the design of TOTEM very forward T2 telescopes thanks to its characteristics: large active areas, good position and timing resolution, excellent rate capability and radiation hardness. Each o f the four T2 half arms has been fully assembled and equipped with electronics at CERN and systematically tested in the SPS beam line H8 in 2008/09. After some optimization, the operation of the GEM chambers was fully satisfactory and the T2 telescopes we re installed and commissioned in their final positions at the LHC interaction point. During the first LHC run (December 2009) the T2 telescopes have collected data, at 900 GeV and 2.36 TeV. We will present here the performances of the detector and the pre liminary results obtained using the data collected
Rate-capability of the VMM3a front-end in the RD51 Scalable Readout System
No full textThe VMM3a is an Application Specific Integrated Circuit (ASIC), specifically developed for the readout of gaseous detectors. Originally developed within the ATLAS New Small Wheel (NSW) upgrade, it has been successfully integrated into the Scalable Readout System (SRS) of the RD51 collaboration. This allows, to use the VMM3a also in small laboratory set-ups and mid-scale experiments, which make use of Micro-Pattern Gaseous Detectors (MPGDs). As part of the integration of the VMM3a into the SRS, the readout and data transfer scheme was optimised to reach a high rate-capability of the entire readout system and profit from the VMM3a’s high single-channel rate-capability of 3.6Mhits/s. The optimisation focused mainly on the handling of the data output stream of the VMM3a, but also on the development of a trigger-logic between the front-end cards and the DAQ computer. In this article, two firmware implementations of the non-ATLAS continuous readout mode are presented, as well as the implementation of the trigger-logic. Afterwards, a short overview on X-ray imaging results is presented, to illustrate the high rate-capability from an application point-of-view.The VMM3a is an Application Specific Integrated Circuit (ASIC), specifically developed for the readout of gaseous detectors. Originally developed within the ATLAS New Small Wheel (NSW) upgrade, it has been successfully integrated into the Scalable Readout System (SRS) of the RD51 collaboration. This allows, to use the VMM3a also in small laboratory set-ups and mid-scale experiments, which make use of Micro-Pattern Gaseous Detectors (MPGDs). As part of the integration of the VMM3a into the SRS, the readout and data transfer scheme was optimised to reach a high rate-capability of the entire readout system and profit from the VMM3a's high single-channel rate-capability of 3.6 Mhits/s. The optimisation focused mainly on the handling of the data output stream of the VMM3a, but also on the development of a trigger-logic between the front-end cards and the DAQ computer. In this article, two firmware implementations of the non-ATLAS continuous readout mode are presented, as well as the implementation of the trigger-logic. Afterwards, a short overview on X-ray imaging results is presented, to illustrate the high rate-capability rom an application point-of-view
Magnetic Moments of Short-Lived Nuclei with Part-per-Million Accuracy: Toward Novel Applications of β-Detected NMR in Physics, Chemistry, and Biology
No full textWe determine for the first time the magnetic dipole moment of a short-lived nucleus with part-per-million (ppm) accuracy. To achieve this 2-orders-of-magnitude improvement over previous studies, we implement a number of innovations into our β-detected nuclear magnetic resonance (β-NMR) setup at ISOLDE at CERN. Using liquid samples as hosts, we obtain narrow, subkilohertz-linewidth, resonances, while a simultaneous in situ 1H NMR measurement allows us to calibrate and stabilize the magnetic field to ppm precision, thus eliminating the need for additional β-NMR reference measurements. Furthermore, we use ab initio calculations of NMR shielding constants to improve the accuracy of the reference magnetic moment, thus removing a large systematic error. We demonstrate the potential of this combined approach with the 1.1 s half-life radioactive nucleus 26Na, which is relevant for biochemical studies. Our technique can be readily extended to other isotopic chains, providing accurate magnetic moments for many short-lived nuclei. Furthermore, we discuss how our approach can open the path toward a wide range of applications of the ultrasensitive β-NMR in physics, chemistry, and biology.sponsorship: This work was supported by the European Research Council (Starting Grant No. 640465), CERN (BetDropNMR and gammaMRI MA Fund), the United Kingdom Science and Technology Facilities Council (No. ST/P004423/1), FWO-Vlaanderen in Belgium (No. G0B3415N), KU Leuven (No. GOA 15/010), EU project ENSAR2 (No. 654002), Slovak Research and Development Agency Grant (No. APVV-15-0105), European Regional Development Fund, Research and Innovation Operational Program (No. ITMS2014+: 313011W085), Polish National Science Centre (OPUS research Grant No. 2017/27/B/ST4/00485), the Ministry of Education, Youth and Sports of the Czech Republic (No. LM2015058), the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (No. 05E15CHA), and the Swiss Excellence Scholarship program. Computational resources of the Slovak Academy of Sciences and the Slovak University of Technology were used (Projects No. ITMS 26230120002 and No. ITMS 26210120002). We thank the assistance of the ISOLDE technical team and that of L. Hemmingsen from Copenhagen University, M. Walczak from Poznan University of Technology, K. Szutkowski from A. Mickiewicz University in Poznan, M. Jankowski, R. Engel, and W. Neu from Oldenburg University, H. Heylen, A. Beaumont, and M. Van Stenis from CERN, V. Araujo from KU Leuven, A. Zhuravlova from Kiev University, K. Jackowski, M. Piersa, and E. Adamska from Warsaw University, J. Klimo, R. Urban, S. Komorovsky, G. Kantay, and J. Krajnak from the Slovak Academy of Sciences, E. Sistare from Geneva University, and M. Jaszunski from the Polish Academy of Sciences. (European Research Council|640465, CERN (BetDropNMR), United Kingdom Science and Technology Facilities Council|ST/P004423/1, FWO-Vlaanderen in Belgium|G0B3415N, KU Leuven|GOA 15/010, EU project ENSAR2|654002, Slovak Research and Development Agency|APVV-15-0105, European Regional Development Fund, Research and Innovation Operational Program|ITMS2014+: 313011W085, Polish National Science Centre (OPUS)|2017/27/B/ST4/00485, Ministry of Education, Youth and Sports of the Czech Republic|LM2015058, Wolfgang Gentner Program of the German Federal Ministry of Education and Research|05E15CHA, Swiss Excellence Scholarship program, CERN (gammaMRI MA Fund), ITMS 26230120002, ITMS 26210120002, STFC|ST/P004423/1, Science and Technology Facilities Council|ST/P004423/1, Science and Technology Facilities Council|ST/L005794/1)status: Published onlin
Design and construction of the triple GEM detector for TOTEM
No full textWe describe the design and construction of the first triple-GEM chamber prototypes for the TOTEM detector at CERN LHC. The chambers are semicircular, with an inner and outer radius of the active area of about 40 and 150 mm; six to eight detectors will be mounted on each arm. Each chamber has analogue readout of the charge on concentric circular strips, at 400 mu m pitch, to obtain the radial coordinates, and about 1000 pads of sizes between 3*3 and 7*7 mm/sup 2/ with digital readout, used to generate the triggering in combination with the other chambers
Radiation imaging with optically read out GEM-based detectors
No full textModern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible scintillating gases and the strong signal amplification factors achieved by MPGDs makes optical readout an attractive alternative to the common concept of electronic readout of radiation detectors. Outstanding signal-to-noise ratios and robustness against electronic noise allow unprecedented imaging capabilities for various applications in fields ranging from high energy physics to medical instrumentation
3D printing of gaseous radiation detectors
No full textAdditive manufacturing techniques such as 3D printing offer unprecedented flexibility in realising intricate geometries. Fused-filament fabrication and high-precision inkjet 3D printing of metals and polymers was used to create functional composite structures, which were operated as radiation detectors. Electron avalanche multiplication in a 3D printed structure was achieved. We present an ionisation chamber and a coarse 2D readout anode with orthogonal strips, which were printed with PLA and graphite-loaded PLA . High-resolution inkjet 3D printing was used to create a Thick Gaseous Electron Multiplier (THGEM) . This represents the first realisation of a fully 3D printed structure achieving electron multiplication. Optical readout was used to quantify the gain factor of the structure and an image under X-ray irradiation was acquired. While the hole geometry of this prototype device inhibited high gain factors, it demonstrates that additive manufacturing is a viable approach for creating detector structures. The conventional manufacturing approach by photolithographic techniques will continue to dominate large size and volume production of MicroPattern Gaseous Detectors (MPGDs) but prototyping and results-driven detector optimisation may greatly benefit from the cost and time-effectiveness of 3D printing
The planispherical chamber: A parallax-free gaseous X-ray detector for imaging applications
No full textCrystallography or X-ray fluorescence experiments which require good signal to noise ratios and high position resolution can take advantage of the outstanding signal amplification capabilities of MicroPattern Gaseous Detectors (MPGDs) such as Gaseous Electron Multipliers (GEMs) coupled with the position resolution achieved by optical readout realized with CCD or CMOS cameras. Increasing the detection probability of incident radiation with thicker drift volumes in these detectors leads to a spatial resolution-limiting parallax error when employing parallel electric field lines in the drift region
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