MINOS is a new apparatus dedicated to in-beam nuclear structure experiments with low-intensity exotic beams in inverse kinematics at intermediate energies above 150MeV/nucleon. The device is composed ...of a thick liquid-hydrogen target coupled to a compact time projection chamber (TPC) serving as a vertex tracker. Either used for in-beam gamma spectroscopy of bound excited states or invariant-mass spectroscopy of unbound states, MINOS aims at improving the luminosity by a very significant factor compared to standard solid-target material experiments while improving experimental resolutions.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Saclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be ...produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In the frame of the in-kind contribution agreement signed with ESS, CEA is going to deliver to the European Spallation Source five Non-invasive Profile Monitors (NPMs) to be installed in the Cold ...Linac section. The high density of the proton bunches, typically 109 proton in a few mm3, may lead to space-charge effect distorting the profile measurements. Studies to contain the space charge effects have been performed. Two different read-outs (current reading from metallic strips and optical) were proposed and tested in two measurement campaigns at the IPHI accelerator at CEA Saclay. After careful analysis, the final choice fell on the read-out composed by a micro channel plate equipped with a phosphorous screen and followed by a camera. The detectors are now in construction at CEA. A summary of all main steps of the project, with special focus on the space charge simulations and the experimental campaigns, will be presented.
Micromegas for beam loss monitoring Segui, L; Alves, H; Aune, S ...
Journal of physics. Conference series,
04/2020, Volume:
1498, Issue:
1
Journal Article
Peer reviewed
Open access
The early detection of beam losses and the alarm to the machine protection system in accelerators are crucial for the safe operation of the machine. In the low energy region of the hadron ...accelerators, only neutrons and photons are produced in the case of a beam loss. However, photons are also emitted by electrons at the RF cavities, becoming a natural background for losses identification. A new kind of beam loss monitors have been conceived to extend the sensitivity to the low energy region of the high intensity hadron accelerators. They are based on Micromegas detectors sensitive to fast neutrons. The appropriate configuration of the Micromegas operating conditions will allow a fast response, a sensitivity to small beam losses and a suppressed sensitivity to photons. In this paper the operation principle and the system developed for the European Spallation Source will be presented, with focus on the results obtained at different irradiation facilities. First time proof of operation in real conditions, with the detection of beam losses, will be also shown with measurements performed at LINAC4 (CERN).
We present first discharge rate measurements for Micromegas detectors in the presence of a high longitudinal magnetic field in the GeV kinematical region. Measurements were performed by using two ...Micromegas detectors and a photon beam impinging a CH
2 target in the Hall B of the Jefferson Laboratory. One detector was equipped with an additional GEM foil, and a reduction of the discharge probability by two orders of magnitude compared to the stand-alone Micromegas was observed. The detectors were placed in the FROST solenoid providing a longitudinal magnetic field up to 5
T. It allowed for precise measurements of the discharge probability dependence with a diffusion-reducing magnetic field. Between 0 and 5
T, the discharge probability increased by a factor of 10 for polar angles between 19° and 34°. A GEANT4-based simulation developed for sparking rate calculation was calibrated against these data in order to predict the sparking rate in a high longitudinal magnetic field environment. This simulation is then used to investigate the possible use of Micromegas in the Forward Vertex Tracker (FVT) of the future CLAS12 spectrometer. In the case of the FVT a sparking rate of 1
Hz per detector was obtained at the anticipated CLAS12 luminosity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
6.
Discharge studies in micromegas detectors in a 150 GeV/c pion beam Procureur, S; Aune, S; Ball, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Volume:
659, Issue:
1
Journal Article
Peer reviewed
A detailed study of several Micromegas detectors prototyped for the COMPASS and CLAS12 experiments is presented. Using a 150 GeV/c pion beam, the discharge probability was measured for several ...detector variants including bulk and non-bulk Micromegas. A detector equipped with an additional GEM foil as pre-amplification stage was also tested. A resistive coating of the readout strips was found to reduce the amplitude of the discharge by at least two orders of magnitude which was below the detection limit of the experimental setup. The effects of the micro-mesh type and material were investigated as well as the influence of the drift gap. Response in the presence of a 1.5 T transverse magnetic field was also studied. The measurements presented were performed during a RD51 beam test period.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
7.
Operation of a resistive Micromegas in air Procureur, S.; Attié, D.; Aune, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2012, Volume:
688
Journal Article
Peer reviewed
The recent developments on resistive Micromegas have enhanced the performance of this detector, and in particular have offered the possibility to reach higher amplification gains in stable operation. ...In this paper, the detection capabilities of a resistive Micromegas in air have been investigated. A clear Fe55 spectrum has been obtained, as well as MIP signals using cosmic rays. In the latter case, the detection efficiency reaches 42%, and could probably be further improved. The stable operation of a gaseous detector in air, i.e. without bottles, pipes or safety systems, can lead to many new applications or simplifications of existing setups.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
8.
The CLAS12 Micromegas Vertex Tracker Acker, A.; Attié, D.; Aune, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2020, Volume:
957, Issue:
C
Journal Article
Peer reviewed
Open access
The Micromegas Vertex Tracker was designed to improve upon the tracking capabilities of the baseline design of the CLAS12 spectrometer in Hall B at Jefferson Laboratory. A Barrel Micromegas Tracker ...made with six concentric cylinders, each made of three 120∘-sector tiles, surrounds the Silicon Vertex Tracker, and a Forward Micromegas Tracker composed of 6 disks is placed 30 cm downstream of the liquid-hydrogen target. Both trackers sit in a 5 T solenoid magnetic field. All Micromegas elements are based on resistive technology to withstand luminosities up to 1035 cm−2 s−1, as well as on bulk technology to enforce gain uniformity and mechanical robustness. Due to the high magnetic field, dedicated electronics have been designed and displaced ∼2 m away from the detectors. The electronics readout is based on the DREAM ASICs that allow sustained operation up to 20 kHz trigger rate at the maximum luminosity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Discharge studies in Micromegas detectors in low energy hadron beams Charles, G.; Anfreville, M.; Aune, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2011, Volume:
648, Issue:
1
Journal Article
Peer reviewed
We present measurements of discharge rates in various Micromegas detectors in low energy hadron beams for applications foreseen at the future experiments CLAS12 at JLab and MINOS at GSI. The tests ...were performed in the T11 beam line of the CERN/PS using hadron beams with momentum between 0.2 and 3GeV/c. The discharge probability decreases smoothly below 1GeV/c, except at some specific energies where narrow peaks are observed. The position of the peaks corresponds to the stop point of protons and heavier particles, predicted by the Geant4 simulation. Discharge rates were also measured using Micromegas prototypes equipped with a GEM foil as foreseen for the COMPASS experiment at CERN.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
10.
Tracking with the MINOS Time Projection Chamber Santamaria, C.; Obertelli, A.; Ota, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2018, Volume:
905
Journal Article
Peer reviewed
We report on the performance of the MINOS Time Projection Chamber developed as a vertex tracker to study exotic nuclei produced from hydrogen-induced knockout via in-beam γ-ray and invariant-mass ...spectroscopy. In-beam measurements with 4He and 20Ne beams at 200 and 350 MeV/nucleon, respectively, were performed at the HIMAC facility. The tracking algorithm for protons after quasi-free scattering is described. Realistic simulations and physics experiments are compared and show a good agreement. The vertex position resolution reaches 5 mm FWHM, mostly from re-scattering with the target and the Aluminum reaction chamber. The overall efficiency of vertex reconstruction is also benchmarked with the first experimental campaign data performed at the RIBF, confirming an overall efficiency better than 90% for physics experiments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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