Test Beam Measurements Research Articles

The CBM-RICH detector

The main task of the future Compressed Baryonic Matter experiment (CBM), to be operatedat the FAIR facility at GSI, Darmstadt, is the exploration of theproperties of super-dense nuclear matter. The search for in-mediummodifications of hadrons, the study of the transition from densehadronic matter to quark-gluon matter, and the possible location of acritical endpoint in the QCD phase diagram of strongly interactingmatter are the most important physics goals of CBM. Detailedmeasurements of di-leptons stemming from low-mass vector-mesons andcharmonium have a large potential to shed light on the existence ofsuch effects.The Ring Imaging Cherenkov detector of the CBM experiment aims at aclean and efficient electron identification. It is foreseen to useCO2 as radiator gas and equip the detector with a focussing mirrorsystem and multi-anode photomultiplier tubes as photon detector. Inthis paper we present selected results of R&D studies and beam testmeasurements of the detector prototype performed in fall 2011 and 2012at the CERN/PS with a mixed electron-pion beam.

Heavily irradiated N-in-p thin planar pixel sensors with and without active edges

We present the results of the characterization of silicon pixel modules employing n-in-pplanar sensors with an active thickness of 150 μm, produced at MPP/HLL, and 100–200 μm thin active edge sensor devices, produced at VTT in Finland.These thin sensors are designed as candidates for the ATLAS pixel detector upgrade to be operated at the HL-LHC, as they ensure radiation hardness at high fluences. They are interconnected to theATLAS FE-I3 and FE-I4 read-out chips.Moreover, the n-in-p technology only requires a single side processing and thereby it is a cost-effectivealternative to the n-in-n pixel technology presently employed in the LHC experiments.High precision beam test measurements of the hit efficiency have been performed on thesedevices both at the CERN SpS and at DESY, Hamburg. We studied the behavior of thesesensors at different bias voltages and different beam incident angles up to the maximum oneexpected for the new Insertable B-Layer of ATLAS and for HL-LHC detectors.Results obtained with 150 μm thin sensors, assembled with the new ATLAS FE-I4 chip andirradiated up to a fluence of 4 × 1015 neq/cm2, show that they are excellent candidates for largerradii of the silicon pixel tracker in the upgrade of the ATLAS detector at HL-LHC. In addition, the active edge technologyof the VTT devices maximizes the active area of the sensorand reduces the material budget to suit the requirements for the innermost layers.The edge pixel performance of VTT modules has been investigated at beam test experiments andthe analysis after irradiation up to a fluence of 5 × 1015 neq/cm2 has been performed using radioactive sources in the laboratory.

Performance studies of MicroMegas for the ATLAS experiment

The performance of MicroMegas (MM) has been extensively studied during several test beam campaigns with high energy particle beams at CERN up to the year 2012, and more recently (June 2013) with electron beams at DESY. Main objectives of the tests were to demonstrate that the requirements could be achieved for the upgrade of the ATLAS Muon Spectrometer, where the MicroMegas will be mounted (along with small-strip Thin Gap Chambers — sTGC) on the New Small Wheel for forward muon detection. The MM layout and operating settings have then been chosen to satisfy the ATLAS upgrade requirements and trigger timing constraints. Results for efficiencies, time resolution and spatial resolution for perpendicular and inclined tracks are presented. Moreover, in ATLAS the MM will operate in a non-uniform magnetic field up to 0.3 T. Dedicated test beam measurements have been carried out in a variable magnetic field between 0 and 1 T. The performance of MM in magnetic fields is also reported along with a comparison to simulations.

Recent results of the ATLAS upgrade planar pixel sensors R&D project

To extend the physics reach of the LHC experiments, several upgrades to the accelerator complex are planned, culminating in the HL-LHC, which eventually leads to an increase of the peak luminosity by a factor of five to ten compared to the LHC design value.To cope with the higher occupancy and radiation damage also the LHC experiments will be upgraded. The ATLAS Planar Pixel Sensor R&D Project is an international collaboration of 17 institutions and more than 80 scientists, exploring the feasibility of employing planar pixel sensors for this scenario.Depending on the radius, different pixel concepts are investigated using laboratory and beam test measurements. At small radii the extreme radiation environment and strong space constraints are addressed with very thin pixel sensors active thickness in the range of (75–150)μm, and the development of slim as well as active edges. At larger radii the main challenge is the cost reduction to allow for instrumenting the large area of (7–10)m2. To reach this goal the pixel productions are being transferred to 6in production lines and more cost-efficient and industrialised interconnection techniques are investigated. Additionally, the n-in-p technology is employed, which requires less production steps since it relies on a single-sided process.An overview of the recent accomplishments obtained within the ATLAS Planar Pixel Sensor R&D Project is given. The performance in terms of charge collection and tracking efficiency, obtained with radioactive sources in the laboratory and at beam tests, is presented for devices built from sensors of different vendors connected to either the present ATLAS read-out chip FE-I3 or the new Insertable B-Layer read-out chip FE-I4. The devices, with a thickness varying between 75μm and 300μm, were irradiated to several fluences up to 2×1016neq/cm2. Finally, the different approaches followed inside the collaboration to achieve slim or active edges for planar pixel sensors are presented.

The Ring Imaging Cherenkov detector for the CBM-Experiment

The mission of the future Compressed Baryonic Matter experiment, to be operated at the FAIR facility at GSI, Darmstadt, is the exploration of the properties of super-dense nuclear matter. In particular, the search for in-medium modifications of hadrons, the study of the transition from dense hadronic matter to quark-gluon matter, and the location of a critical endpoint in the phase diagram of strongly interacting matter are the principal physics goals of CBM. Detailed measurements of di-leptons and open charm probes are hoped to shed light to the existence of such effects.The Ring Imaging Cherenkov detector of CBM aims at a clean and efficient electron identification. It is foreseen to have CO2 as radiator gas and to be equipped with Hamamatsu multi-anode photomultiplier tubes. Herewith we present selected results of R&D studies and beam test measurements of the RICH prototype performed in October 2011 at the CERN/PS with negatively charged particles.

Results with p-type pixel sensors with different geometries for the HL-LHC

Pixel detectors will be extensively used for the four innermost layers of the upgraded ATLAS experiment at the future High Luminosity LHC (HL-LHC) at CERN. The total area of pixel sensors will be over 5m2. The silicon sensors that will instrument the pixel volume will have to face several technology challenges. They will have to withstand doses up to 2×1016neqcm−2, to have a reduced inactive area at the edge of the sensors still being able to hold 1000V bias voltage and to be relatively low cost considering the large area to be covered. N-side readout on p-type bulk is the most promising technology for satisfying the various requirements. Several sensor types have been produced in the UK, conceived for various readout systems, for studying the properties of n-in-p and n-in-n sensors before and after irradiation with test beam and laboratory measurements. The status of these studies is presented here.

Performance of the ATLAS Tile Calorimeter

The Tile Calorimeter is the central section of the ATLAS hadronic calorimeter at the Large Hadron Collider. It is a key detector for the measurement of hadrons, jets, tau leptons and missing transverse energy. Because of its very good signal to noise ratio it is also useful for the identification and reconstruction of muons. The calibration and performance of the calorimeter have been established through test beam measurements, cosmic ray muons and the large sample of pp collisions. Results on the calorimeter performance are presented, including the absolute energy scale, time resolution, and associated stabilities.

Planar pixel sensors for the ATLAS tracker upgrade at HL-LHC

The ATLAS Planar Pixel Sensor R&D Project is a collaboration of 17 institutes and more than 80 scientists. Their goal is to explore the operation of planar pixel sensors for the tracker upgrade at the High Luminosity-Large Hadron Collider (HL-LHC).This work will give a summary of the achievements on radiation studies with n-in-n and n-in-p pixel sensors, bump-bonded to ATLAS FE-I3 and FE-I4 read-out chips. The summary includes results from tests with radioactive sources and tracking efficiencies extracted from test beam measurements. Analysis results of 2×1016neqcm−2 and 1×1016neqcm−2 (1MeV neutron equivalent) irradiated n-in-n and n-in-p modules confirm the operation of planar pixel sensors for future applications.

Geant4 simulation of transition radiation detector based on DEPFET silicon pixel matrices

This paper presents new developments in Monte Carlo simulation for test beam measurements of a silicon transition radiation detector based on DEPFET—a silicon active pixel detector. The test of DEPFET with fiber radiator has been carried out at the DESY 5GeV electron beam. Monte Carlo simulation of the test beam setup is based on Geant4. A comparison of Geant4 simulation with test beam data is presented.

Beam Test Measurements With Planar and 3D Silicon Strip Detectors Irradiated to sLHC Fluences

The planned luminosity upgrade of the CERN LHC to the super LHC (sLHC) requires investigation of new radiation hard tracking detectors. Compared to the LHC, tracking detectors must withstand a 5–10 times higher radiation fluence. Promising radiation hard options are planar silicon detectors with n-side readout and silicon detectors in 3D technology, where columnar electrodes are etched into the silicon substrate. This article presents beam test measurements performed with planar and 3D n-in-p silicon strip detectors. The detectors were irradiated to different fluences, where the maximum fluence was <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$3\times 10^{15}$</tex></formula> 1 MeV neutron equivalent particles per square centimeter <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$({\rm n}_{\rm eq}/{\rm cm}^{2})$</tex></formula> for the planar detectors and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${2\times 10^{15}~{\rm n}_{\rm eq}/{\rm cm}^{2}}$</tex></formula> for the 3D detectors. In addition to signal measurements, charge sharing and resolution of both detector technologies are compared. An increased signal from the irradiated 3D detectors at high bias voltages compared to the signal from the unirradiated detector indicates that charge multiplication effects occur in the 3D detectors. At a bias voltage of 260 V, the 3D detector irradiated to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${2\times 10^{15}~{\rm n}_{\rm eq}/{\rm cm}^{2}}$</tex> </formula> yields a signal almost twice as high as the signal of the unirradiated detector. Only 30% of the signal of an unirradiated detector could be measured with the planar detector irradiated to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${3\times 10^{15}~{\rm n}_{\rm eq}/{\rm cm}^{2}}$</tex></formula> at a bias voltage of 600 V, which was the highest bias voltage applied to this sensor.

The ALICE Electromagnetic Calorimeter: EMCAL

The ALICE Experiment (A Large Ion Collider Experiment) aims to study the properties of quark-gluon matter using Pb-Pb collisions at a center of mass energy (per nucleon pair) of TeV with the Large Hadron Collider (LHC) at CERN. The EMCAL detector is a large area electromagnetic calorimeter. ALICE's capability to perform jet reconstruction is greatly improved by measuring the neutral energy component of jets including photons and neutral pions. The calorimeter produces also a fast, high-pT trigger providing an enhancement in high-pT events, participates in the High Level Trigger (HLT), performing online reconstruction at the full data rates and generates trigger information based on reconstructed events. The performance of prototypes has been studied in test beam measurements at FNAL and CERN and are shown. Four EMCAL super-modules have been installed at CERN and are operational. First results from data taking are presented. Moreover, an extension of EMCAL for jet-jet and γ-jet physics will be discussed.

New insights into particle detection with superheated liquids

We report new results obtained from calibrations of superheated liquid droplet detectors used in dark matter searches with different radiation sources (n, α, γ). In particular, detectors were spiked with α-emitters located inside and outside the droplets. It is shown that the responses have different temperature thresholds, depending on whether α-particles or recoil nuclei create the signals. The measured temperature threshold for recoiling 210Pb nuclei from 214Poα-decays was found to be in agreement with test beam measurements using mono-energetic neutrons. A comparison of the threshold data with theoretical predictions shows deviations, especially at high temperatures. It is shown that signals produced simultaneously by recoil nuclei and α-particles have more acoustic energy than signals produced by one or the other separately. A model is presented that describes how the observed intensities of particle-induced acoustic signals can be related to the dynamics of bubble growth in superheated liquids. A growth scenario that is limited by the inertia of the surrounding liquid shows a trend that is supported by the data. An improved understanding of the bubble dynamics is an important first step in obtaining better discrimination between particle types interacting in detectors of this kind.

Studies of Scintillator Tiles with SiPM Readout for Imaging Calorimeters

Imaging hadronic calorimeters with scintillator readout use small scintillator tiles individually read out by silicon photomultipliers to achieve the necessary granularity needed for sophisticated reconstruction algorithms at future collider detectors. For a second generation prototype of the CALICE analog HCAL new, 3 mm thick scintillator tiles with an embedded wavelength shifting fiber and new photon sensor from CPTA are being fabricated. The availability of blue-sensitive SiPMs also allows fiberless coupling of the photon sensor to the tile, a technique requiring modified geometries to achieve a high degree of response uniformity. We discuss results from test bench and from test beam measurements of different scintillator tile geometries as well as prospects for fiberless coupling of photon sensors.

Beam Test Measurements With 3D-DDTC Silicon Strip Detectors on n-Type Substrate

For the planned luminosity upgrade of the CERN LHC to the sLHC new radiation hard technologies for the tracking detectors are investigated. Corresponding to the luminosity increase, the radiation dose will be approximately a factor of ten higher than for the detectors currently installed in the LHC experiments. One option for radiation tolerant detectors are 3D silicon detectors with columnar electrodes penetrating into the silicon bulk. This article reports results of beam test measurements performed with 3D-DDTC (Double-Sided, Double Type Column) silicon strip detectors, where the columns do not pass through the detector completely. The devices were produced by IMB-CNM (Barcelona, Spain) and by FBK-irst (Trento, Italy). Important properties like space-resolved charge collection and efficiency are investigated.

The first beam test of a monolithic particle pixel detector in high-voltage CMOS technology

The results of beam- and irradiation tests preformed on a monolithic particle pixel detector in high-voltage CMOS technology will be presented for the first time. All tested detectors are implemented in a 0.35 μ m technology, they utilize high-voltage n-well/p-substrate diodes as pixel sensors and rely on charge drift in diode depletion layers as the main signal generating mechanism. The detector prototype tested in the beam is a system on a chip that contains a 128×128 matrix with 21 × 21 μ m 2 large pixels, source-follower based- rolling shutter readout and on-chip ADCs that digitize the signal amplitudes with 8-bit precision. Test beam measurements have been performed using EUDET infrastructure. The measured MIP cluster signals are typically 2200 e, spatial resolution approximately 7 μ m (RMS), signal-to-noise ratio of a single pixel is 12.3 and detection efficiency more than 85%. To test the radiation tolerance, several detector chips have been irradiated with neutrons up to 10 14 n eq/cm 2 and with X-rays up to 500 kGy (50 Mrad), they are still functional and the experimental results obtained with these chips will be presented as well.

New transition radiation detection technique based on DEPFET silicon pixel matrices

Transition Radiation Detectors (TRD) have the attractive feature of being able to separate particles by their gamma factor. Replacing the xenon based gaseous detectors by modern silicon detectors is complicated by the large energy losses of charged particles in 300 – 700 μ m of silicon. A silicon active pixel detector—DEPFET—has features which allows another detection technique to be used, in order to overcome the existing limitation on separating transition radiation photons with an energy loss from a charged particle in the same pixel. The tests of DEPFET with fiber radiator have been carried out at CERN SPS and DESY beams. The first results of test-beam measurements and Monte Carlo simulation are presented.

Performance of prototypes for the ALICE electromagnetic calorimeter

The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A 4 × 4 array of final design modules showed an energy resolution of about 11 % / E ( GeV ) ⊕ 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm ⊕ 5.3 mm / E ( GeV ) . For an electron identification efficiency of 90% a hadron rejection factor of > 600 was obtained.

The STAR Forward GEM Tracker

The STAR collaboration is preparing a forward tracking detector upgrade, the Forward GEM Tracker (FGT), to provide fundamental studies of the proton spin structure and dynamics in high-energy polarized proton–proton collisions at RHIC at BNL. The FGT is based on triple-GEM technology employing the industrial production of GEM foils by Tech-Etch Inc. and a laser-etched two-dimensional readout board manufactured by Compunetics Inc. The FGT project has completed an extensive R&D program of industrially produced GEM foils at Tech-Etch Inc. in comparison to GEM foils produced at CERN based on optical measurements and 55Fe source and testbeam measurements of a triple-GEM prototype detector using 10 × 10 cm 2 GEM foils. The FGT project requires large GEM foils which are currently being tested.

The EUDET high resolution pixel telescope

Within the EUDET consortium a high resolution pixel beam telescope is being developed. The telescope consists of up to six planes of monolithic active pixel sensors and can be operated in a magnetic field of 1.2 T. A flexible data acquisition environment is available for the telescope and the system is equipped with all the required infrastructure. Since the first installation of a demonstrator telescope in 2007, it has been extensively tested and used by various detector R&D groups. The results of test beam measurements are described here, demonstrating the telescope performance. The sensors of the final telescope will provide digital outputs and zero suppression.

The LHCb Detector at the LHC

The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.