Endcap Electromagnetic Calorimeter Research Articles

Novel 4x4 SiPM array readout with integrated preamplification stage, optimized for the PWO detectors of the EIC EEEMCal

We are reporting on a new readout circuit developed for the lead tungstate (PbWO4) scintillation detectors for the Electron Ion Collider (EIC) Electron Endcap Electromagnetic Calorimeter EEEMCal. The high magnetic field region precludes the use of photomultiplier tubes while the detector requirements specify good spectral resolution performance and fast pulse integration over a large dynamic range. We selected a silicon photomultiplier (SiPM) from Hamamatsu and produced a matrix of 4 x 4 sensors to cover the 20 mm × 20 mm scintillator coupling surface. Signal acquisition and amplification electronics boards were designed and integrated with the sensor board to produce a compact high performance readout package. A prototype detector was built and tested at Jefferson Lab with encouraging resolution and timing performance results.

Open-Hardware and Application Specific Design for the Monitoring System of the Belle II Forward/Backward Electromagnetic Calorimeter

Control and monitoring of experimental facilities as well as laboratory equipment requires handling a blend of different tasks. Often in industrial or scientific fields there are standards or form factor to comply with and electronic interfaces or custom busses to adopt. With such tight boundary conditions, the integration of an off-the-shelf Single Board Computer (SBC) is not always a possible or viable alternative. The availability of electronic schematics and PCBs with open-source Hardware license for various SBCs overcomes such integration problems, making feasible the implementation of a custom architecture composed by a central core inherited from a vendor reference design (most likely the microprocessor, static RAM and flash memory) augmented with application-specific integrated circuits and hardware resources, in order to handle the requirements of the specific environment. The user is then able to exploit most of the supported tools and software provided by opensource community, fulfilling all the constraints enforced by his environment. We have used such an approach for the design and development of the monitoring system of the endcap electromagnetic calorimeter of the Belle II experiment, presently running at KEK Laboratory (Tsukuba, Japan). Here we present and discuss the main aspects of the hardware architectures and noise performances tailored on the needs of a detector designed around CsI crystal scintillators.

Geometric alignment of the CMD-3 endcap electromagnetic calorimeter using events of two-quantum annihilation

Since 2010 the electromagnetic endcap calorimeter based on BGO crystals is used in experiments as one of the systems of the CMD-3 detector. The spacial resolution is one of crucial parameters of the calorimeter. Inaccurate knowledge of the real calorimeter position can limit the resolution. In this work the alignment of the center of the calorimeter with respect to the tracking system of the CMD-3 detector has been performed using events of two-quantum annihilation. The alignment technique that has been used to determine the position of the calorimeter is described. Finally, the improvement in spacial resolution of the calorimeter after applying the correction for the real calorimeter position is shown.

Monitoring complex detectors: the uSOP approach in the Belle II experiment

uSOP is a general purpose single board computer designed for deep embedded applications in control and monitoring of detectors, sensors and complex laboratory equipments. It is based on the AM3358 (1 GHz ARM Cortex A8 processor), equipped with USB and Ethernet interfaces. On-board RAM and solid state storage allows hosting a full LINUX distribution. In this paper we discuss the main aspects of the hardware and software design and the expandable peripheral architecture built around field busses. We report on several applications of uSOP system in the Belle II experiment, presently under construction at KEK (Tsukuba, Japan). In particular we will report the deployment of uSOP in the monitoring system framework of the endcap electromagnetic calorimeter.

Study of a pure CsI crystal readout by APD for Belle II end cap ECL upgrade

A scintillation counter consisting of a pure CsI crystal and avalanche photodiodes (Hamamatsu APD S8664-55 and S8664-1010) has been studied for the upgrade of the end cap electromagnetic calorimeter of Belle II detector. An essential increase of the light output was achieved with wavelength shifters based on nanostructured organosilicon luminophores.

Neutral pion cross section and spin asymmetries at intermediate pseudorapidity in polarized proton collisions ats=200 GeV

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η<2.0 in polarized proton-proton collisions at s=200 GeV are presented. Neutral pions were detected using the end cap electromagnetic calorimeter in the STAR detector at RHIC. The cross section was measured over a transverse momentum range of 5<pT<16 GeV/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry ALL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured ALL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry AL is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and pT. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed at more forward pseudorapidity (η≈3) and their underlying mechanisms. The AN results presented are consistent with a twist-3 model prediction of a small asymmetry over the present kinematic range.2 MoreReceived 6 September 2013DOI:https://doi.org/10.1103/PhysRevD.89.012001© 2014 American Physical Society

Alignment of the CMS Preshower detector

The Preshower detector, as part of the CMS endcap electromagnetic calorimeter, is designed to identify π0 in the endcaps within a fiducial region 1.653<|η|<2.6. It is based on 4288 silicon sensors, each with active area 61×61mm2 segmented into 32 strips with 1.9 mm pitch. For minimum ionizing particles the intrinsic spatial precision is 17.6mm parallel to the strip and 550μm perpendicular to the strips. Exploiting its spatial resolution relies upon excellent alignment with the neighboring detectors, especially the Tracker.The alignment is based on the extrapolation of tracks from the Tracker to the Preshower and gives an alignment precision of a few millimeters for translation and a few milliradians for rotation. The method for Preshower alignment is discussed and the results of the alignment with respect to the Tracker, using LHC collision data collected by CMS in 2011, are given.

Rapidity dependence of azimuthal correlations for p+p and d+Au at √s = 200GeV

Forward di-jet production in d+Au collisions at RHIC provides sensitivity to Bjorken-x between 0.001 and 0.02 for the nuclear gluon density. The STAR experiment at RHIC has continuous azimuthal coverage with electromagnetic calorimeters for pseudo-rapidity from-1 to 4. We have measured forward+mid-rapidity π0 − π0 and π0 − h azimuthal correlations and forward+forward rapidity π0 − π0 azimuthal correlations. Both analyses use the Forward Meson Spectrometer (FMS) triggered data in RHIC 2008 run p+p and d+Au collisions at = 200 GeV. The end-cap electromagnetic calorimeter (EEMC) at STAR covers pseudo-rapidity from 1.07 to 2. This provides us sensitivity to the nuclear gluon density at intermediate x values. Preliminary results on the π0 − π0 and π0 + jet-like azimuthal correlations with both the FMS and the EEMC will be discussed.

Performance, Calibration and Alignment of the CMS Preshower Detector

The Preshower detector, part of the CMS Endcap Electromagnetic Calorimeter, is designed to have good spatial resolution to identify the position of incoming particles. The detector was installed in CMS and commissioned in 2009. LHC collisions provided data used to verify the calibration of the Preshower silicon sensors, and compare low-level observables such as energy deposits and clustering with Monte-Carlo - showing good agreement. The data also allowed an alignment measurement to be performed between the Preshower and the Tracker.

The commissioning and first results on the performance of the CMS Preshower Detector

The Preshower is the first part of the CMS endcap electromagnetic calorimeter, as seen by the particles. It is composed of 2 layers of lead absorbers followed by silicon sensors of a total surface of 17 m2 the biggest ever built. The use of the silicon strip sensors improves the spatial accuracy of the incidence position of electromagnetic showers. This allows an additional rejection of background (e.g. neutral pions) to new physics, such as the two-photon SM Higgs decay. In this article, the results from first commissioning, the performance with first LHC beams and first in-situ calibration with charged particles are described.

Luminosity monitoring and calibration of BLM

The BEPCII Luminosity Monitor (BLM) monitors relative luminosity per bunch. The counting rates of gamma photons, which are proportional to the luminosities from the BLM at the center of mass system energy of the ψ (3770) resonance, are obtained with a statistical error of 0.01% and a systematic error of 4.1%. Absolute luminosities are also determined by the BESIII End-cap Electro-Magnetic Calorimeter (EEMC) using Bhabha events with a statistical error of 2.3% and a systematic error of 3.5%. The calibration constant between the luminosities obtained with the EEMC and the counting rates of the BLM are found to be 0.84±0.03 (×1026 cm−2·count−1). With the calibration constant, the counting rates of the BLM can be scaled up to absolute luminosities.

The production of radiation tolerant vacuum phototriodes and their HV filters for the Compact Muon Solenoid endcap electromagnetic calorimeter

Particle detectors which will operate at the Large Hadron Collider face unprecedented challenges in both the number of active detector elements and in operating without maintenance in a high radiation environment for many years. In the Compact Muon Solenoid (CMS) detector the scintillating crystal electromagnetic calorimeter uses vacuum photodetectors in the endcap where the lifetime neutron and hadron fluence is too high for the silicon avalanche photodiodes used in the barrel. Over 15000 radiation tolerant vacuum phototriodes (VPT) have been now been produced by industry for the endcap calorimeter. The VPT have to operate in an environment which has both a significant lifetime dose (up to 50 kGy) from electrons and gamma rays and a high neutron fluence (up to nearly 10 15 n.cm −2 for E > 100 keV). This paper discusses the steps taken during both the development and production of the VPT to ensure that the response to the scintillation light from the lead tungstate scintillator will not be significantly degraded during the operational lifetime of the experiment. Data from the quality assurance procedures and radiation induced degradation of complete VPT devices is presented. Other components of the endcap calorimeter are also exposed to a similarly intense radiation field. The quality assurance procedure used to select the passive components (resistors and capacitors) used in the high-voltage filter cards is described.

Electromagnetic secondaries and punch-through effects in the CMS ME1/1

The aim of this work is to estimate the shower leakage from the CMS Endcap Hadron calorimeter (HE) due to electromagnetic secondaries and punch-through in the region of the ME1/1 Forward Muon Station. Two configurations are considered: with and without the CMS Endcap Electromagnetic calorimeter (EE). The experimental data have been taken during the combined beam test of CMS subdetectors (HE, ME, RPC, DT) at the CERN H2 beam facility in 2004. Serial CSC chambers (ready for installation in CMS) fully equipped with readout electronics have been exposed. Simulation of a beam test setup has been performed using the GEANT4-based simulation software package OSCAR.

Simulation of a vacuum phototriode with SIMION 3D

An electron-optic model of a 26 mm diameter vacuum phototriode (VPT) photodetector was developed using SIMION 3D software extended by additional code to simulate secondary emission at the dynode. The predictions of the variation of gain with magnetic field for mesh anodes with 100, 40 and 7 lines per mm and fields from 0 and 4 T are presented. The predicted time development of the signal at 0 T is presented and compared with experimental data obtained by illuminating a production VPT for the electromagnetic endcap calorimeter of CMS with 60 ps laser pulses at a wavelength of 435 nm.

The ATLAS liquid argon hadronic end-cap calorimeter: construction and selected beam test results

ATLAS has chosen for its Hadronic End-Cap Calorimeter (HEC) the copper-liquid argon sampling technique with flat plate geometry and GaAs pre-amplifiers in the argon. The contruction of the calorimeter is now approaching completion. Results of production quality checks are reported and their anticipated impact on calorimeter performance discussed. Selected results, such as linearity, electron and pion energy resolution, uniformity of energy response, obtained in beam tests both of the Hadronic End-Cap Calorimeter by itself, and in the ATLAS configuration where the HEC is in combination with the Electromagnetic End-Cap Calorimeter (EMEC) are described.

Development and large-scale production of ceramic PCBs for the preshower detector of the CMS experiment

Fabrication of printed circuit boards (PCBs) in high-radiation areas requires new technologies. The CMS detector in the CERN Large Hadron Collider will have portions in high-radiation environment. The preshower detector in front of the endcap electromagnetic calorimeter is such an area. During the past several years, the emphasis has been put on the research and development of individual components of the preshower detector. Several prototypes of PCBs were manufactured on ceramic substrates. The final prototype was a high-quality product with the ceramic board meeting all specifications, including the adherence of metallic pastes, the resistivity of the metallic lines and the precision of the laser cutting. The Yerevan Physics Institute in collaboration with the MARS Factory, Rubin L. Tech. JSC and Yerevan Telecommunication Research Institute made 4.500 units of the ceramics PCBs and are now being incorporated in the preshower detector. This article describes in detail the R&D for the technology of thick film printing on a ceramic substrate with different pastes and the precise cutting of ceramic plates by a laser.

The response to high magnetic fields of the vacuum phototriodes for the Compact Muon Solenoid endcap electromagnetic calorimeter

The endcap electromagnetic calorimeter of the compact muon solenoid detects particles with the dense fast scintillator lead tungstate (PbWO4). Due to the low light yield of this scintillator, photodetectors with internal gain are required. Silicon avalanche photodiodes cannot be used in the endcap region due to the intense neutron flux. Following an extensive R&D programme, 26mm diameter single-stage photomultipliers (vacuum phototriodes) have been chosen as the photodetector in the endcap region. The first 1400 production devices are currently being evaluated following recent tests of a pre-production batch of 500 tubes. Tubes passing our acceptance tests have responses, averaged over the angular acceptance of the endcap calorimeter, corresponding to the range 20–55electrons/MeV deposited in PbWO4. These phototriodes operate, with a typical gain of 10, in magnetic fields up to 4T.

Performance of the ATLAS electromagnetic calorimeter end-cap module 0

The construction and beam test results of the ATLAS electromagnetic end-cap calorimeter pre-production module 0 are presented. The stochastic term of the energy resolution is between 10% and 12.5% GeV 1/2 over the full pseudorapidity range. Position and angular resolutions are found to be in agreement with simulation. A global constant term of 0.6% is obtained in the pseudorapidity range 2.5< η<3.2 (inner wheel).

The STAR endcap electromagnetic calorimeter

The STAR endcap electromagnetic calorimeter will provide full azimuthal coverage for high- p T photons, electrons and electromagnetically decaying mesons over the pseudorapidity range 1.086⩽ η⩽2.00. It includes a scintillating-strip shower-maximum detector to provide π 0/γ discrimination and preshower and postshower layers to aid in distinguishing between electrons and charged hadrons. The triggering capabilities and coverage it offers are crucial for much of the spin physics program to be carried out in polarized proton–proton collisions.

Fine-mesh photodetectors for CMS endcap electromagnetic calorimeter

The behaviour of fine-mesh vacuum phototriodes (VPTs) with the external diameters of 21 and 25 mm has been investigated in an axial magnetic field up to 4 T in view of their applications as readout devices for CMS Endcap Electromagnetic Calorimeter. The measured VPT parameters are: the photocathode's sensitivity and its homogeneity, the gain in zero and 4 T magnetic field at tilt angles corresponding to the pseudorapidity range of CMS ECAL Endcap 1.48–3.0 as a function of fine-mesh cell dimensions, excess noise factor and the stability of the photocathode response under the illumination by light emission diodes (LED) and the irradiation by 14 MeV neutrons. Phototriodes with 100 lines per mm fine-mesh and 25 mm external diameter are found to be the best candidates for coupling with rear PbWO4 crystals by dimensions of 30×30 mm, proposed to be used in CMS ECAL Endcaps. VPTs provide a gain of the order (6–8) in a 4 T magnetic field and an excess noise factor of 2–2.5 under illumination of a full photocathode's area.