Preshower Detector Research Articles

The first test of a monolithic silicon pixel detector ASIC for the detection of electromagnetic showers of TeV energy in the FASER experiment at the LHC

The FASER experiment at the LHC is designed to look for new, long-lived fundamental particles. A W-Si preshower detector is currently under construction, with the objective of enabling the discrimination of photon pairs with O(TeV) energies and separation down to 200 μm, extending the discovery potential of the experiment. The detector will be based on a new monolithic silicon pixel sensor in 130 nm SiGe BiCMOS. The first test of the ASIC from a pre-production run shows that the building blocks of the monolithic silicon pixel detector are functional.

The new monolithic ASIC of the preshower detector for di-photon measurements in the FASER experiment at CERN

The ForwArd Search ExpeRiment (FASER) is an experiment searching for new light and weakly-interacting particles at CERN’s Large Hadron Collider. FASER is composed of different sub-detectors, including silicon microstrip detectors, scintillator counters and an electromagnetic calorimeter. In this paper, a new preshower detector for the FASER experiment is presented. The new detector, based on monolithic pixel ASICs, will provide excellent spatial and time resolutions and a large charge dynamic range. First results from a prototype chip produced by IHP in 130 nm SiGe BiCMOS technology are shown.

The [formula omitted]-RWELL technology for the preshower and muon detectors of the IDEA detector

The IDEA detector concept has been designed to operate at a future large circular e+e− collider, like FCC-ee or CEPC. The IDEA detector has an innovative design with a central tracker enclosed in a superconducting solenoidal magnet. Going outwards, a preshower system followed by a dual readout calorimeter is foreseen. In the iron yoke, that closes the magnetic field, are then located three stations of muon detectors. The preshower and muon detectors are based on the μ-RWELL technology that inherits the best characteristics of the GEM, in particular the layout of the amplification stage, and Micromega detectors, that inspired the presence of a resistive stage. To profit of the industrial production capabilities of this technology, a modular design has been adopted for both systems: the μ-RWELL tile will have an active area of 50 × 50 cm2, but with a pitch between the readout strips of 400μm for the preshower and about 1 mm for the muon system. Other requirements are: a spatial resolution of the order of 100μm for the preshower and a reasonable total number of front-end channels for the muon system. To optimize the resistivity and the strip pitch, we have built a set of prototypes with active area of 5 × 40 cm2 and 40 cm long strips. The DLC resistivity is ranging from 10 to 80 MΩ/□. All these detectors have been exposed in October 2021 to a muon beam at the CERN SPS. The very positive results obtained pave the way for a completely new and competitive MPGD tracking device for high energy physics experiments.

Detection of collinear high energetic di-photon signatures with Micromegas Detectors

The search for weakly interacting, light particles that couple to photons received significant attention in recent years. When those particles are produced at high energies, they may decay in two collinear photons that can be detected by an electromagnetic calorimeter system. The typical dominant background in searches for those high energetic weakly interacting particles are single, high energetic photons, which leave similar signatures in a standard calorimeter system. One promising approach to separate signal from background events is to employ a dedicated pre-shower detector in front of the calorimeter that can distinguish one- and two-photon signatures. In this work we present a conceptual design of such detector which is able to separate one from two collinear photon signatures. For energies above 300GeV, it allows for efficiencies between 20% to 80% for two photons separated by 100µm to 2000µm, respectively, and a background rejection of more than 90%. Our pre-shower detector design has an active surface area of 10×10cm2, a depth of 230mm and is based on Micromegas detectors operated with Ar:CO2 (93%:7%), thus offering a cost effective solution.

Measurements and analysis of different front-end configurations for monolithic SiGe BiCMOS pixel detectors for HEP applications

This paper presents a small-area monolithic pixel detector ASIC designed in 130 nm SiGe BiCMOS technology for the upgrade of the pre-shower detector of the FASER experiment at CERN. The purpose of this prototype is to study the integration of fast front-end electronics inside the sensitive area of the pixels and to identify the configuration that could satisfy at best the specifications of the experiment. Self-induced noise, instabilities and cross-talk were minimised to cope with the several challenges associated to the integration of pre-amplifiers and discriminators inside the pixels. The methodology used in the characterisation and the design choices will also be described. Two of the variants studied here will be implemented in the pre-production ASIC of the FASER experiment pre-shower for further tests.

PHENIX study of the initial state with forward hadron measurements in 200 GeV p(d)+A and 3He+Au collisions

Forward hadron measurements in p(d)+A provide a signal to study nuclear shadowing, initial state energy loss and/or gluon saturation effects as a function of rapidity, centrality and energy. High pT identified π0 measurements are an essential first step toward measuring prompt photon production. The π0 measurements are enabled by the PHENIX MPC-EX detector, a Si-W preshower detector located in front of the Muon Piston Calorimeter (MPC), expanding the neutral pion reconstruction capabilities in the rapidity range 3.1 <η < 3.8 out to high energies, E < 80 GeV. Previous PHENIX measurements of punch-through charged hadrons in the muon arms in the rapidity range 1.4 < |η| < 2.2 were significantly improved through the capability of the forward silicon vertex detector (FVTX) to determine the transverse momentum and rapidity with high precision and reject background from secondary hadrons.PHENIX collected d+Au data with the MPC-EX in the 2016 run at sNN=200,62,39and19.6GeV; and p+p and p+Au(Al) data with the FVTX in 2015 at 200 GeV. In this talk, we will present first results for high pTπ0 production from the sNN=200GeV dataset, the status of the prompt photon measurement, as well as charged hadron nuclear modification factors in p+Au(Al) and 3He+Au.

CaloCube and “Tracker In Calorimeter” projects for the direct measurement of high energy charged astro-particles and gamma rays.

Measurements of high energy cosmic rays in the “knee” region (about 1015 eV) are currently available only with ground detectors: new observations of cosmic particles up to these energies with direct measurements are one of the main goals of the next generation space experiments. To achieve those aims, a large acceptance, good energy resolution and particle identification are needed. CaloCube is the design of a space borne calorimeter which is capable to accept particles coming from any direction, increasing the acceptance with respect to traditional telescopes. A good performance for both hadronic and electromagnetic showers is achieved with a 3-D sampling capability: the basic picture of CaloCube is a cubic homogeneous calorimeter which consists of cubic scintillating crystals. MC simulations, concerning different materials and geometrical configurations, and several beam tests with different versions of the CaloCube prototype have been employed to optimize both the detector design and the data analysis method. Taking advantage of the CaloCube project, the space experiment HERD (“High Energy Cosmic Radiation Detection”) will include a large acceptance cubic calorimeter with cubic LYSO crystals. It will be installed on-board of the Chinese space station around 2025. Beside the charged particle observations, high energy gamma-rays provide direct information about the galactic cosmic ray sources. A new project named “Tracker In Calorimeter” (TIC) was approved by INFN in 2017 with the main purpose of the optimization of the calorimeter design for the reconstruction of the gamma-ray direction, without the requirement of additional not homogeneous pre-shower detector. A TIC prototype was recently assembled and tested at the PS-CERN and SPS-CERN accelerators.

Participation of JINR in the CDF Experiment

Participation of a Joint Institute for Nuclear Research (JINR) team in the research program at the Tevatron at Fermilab is described. In their work on the upgraded CDF Run II detector, the emphasis was placed on top quark physics. The JINR team was fully engaged in the data analysis of the CDF experiment, particularly, in measuring the top quark mass in the dilepton and lepton–jet modes, in measuring the top quark charge, and in searching for the Higgs boson. The JINR team made a decisive contribution to the operation of the scintillation counter subsystem of the CDF muon trigger, to the trigger based on the vertex silicon detector for selection of events with secondary vertices and to the preshower detector of the electromagnetic calorimeter. The team was involved in the construction, upgrading, and operation of the system of scintillation counters and developed a system for the online monitoring of their parameters to ensure their effective operation in Run II. The work of the JINR researchers was highly appreciated by the international CDF collaboration.

Operation and performance of the LHCb calorimeters

The LHCb calorimeters play a key role in the hardware trigger of the experiment. They also serve the measurement of radiative heavy flavor decays and the identification of electrons. Located at twelve meters from the interaction region, they are composed of a plane of scintillating tiles, a preshower detector, an electromagnetic and a hadronic sampling calorimeters using scintillators as active elements. In these proceedings, technical and operational aspects of these detectors are described. Emphasis is then put on calorimeter reconstruction and calibration. Finally, performance for benchmark physics modes are briefly reported.

Calibration system of the LHCb hadronic calorimeter

The Hadron Calorimeter of LHCb (HCAL) is one of the four sub-detectors of the experiment calorimetric system, which also includes: Scintillator Pad Detector (SPD), Pre-Shower Detector (PS), and electromagnetic (ECAL) calorimeter. The main purpose of HCAL is to provide data for Level-0 trigger for selection events with high transverse energy hadrons. It is important to have a precise and reliable calibration system which produces result immediately after the calibration run. LHCb HCAL is equipped with a calibration system based on 137Cs radioactive source embedded into the calorimeter structure. It allows to obtain absolute calibration with good precision and monitor technical condition of the detector.

New preshower detector for the DIRAC experiment

The Preshower (PSh) detector [1] is a component of the DIRAC setup [2]. It is designed to identify and reject the huge e−e+ pairs background in the ππ and Kπ pairs measurement produced in a hadronic atom ionization process. In the high energy region used for kaon detection, the small Nitrogen Cherenkov detector has low electron rejection efficiency. To increase the overall efficiency, a new two-layer scintillator Preshower detector has been developed and built. The new Preshower–Cherenkov combination ensures an electron rejection efficiency better than 99% in the momentum range 1–7GeV/c.

Effects of damage caused by non-ionizing energy loss in Si Mini-Pad sensors for the PHENIX MPC-EX

The PHENIX MPC-EX is an W/Si pre-shower detector operating at small angles with respect to the beam in the Relativistic Heavy Ion Collider (RHIC). The Si Mini-Pad sensors are the active element of the detector. The expected hadron flux to the Si Mini-Pad sensors will generate significant non-ionizing energy loss in the sensors, which may damage the crystalline structure of the sensor’s bulk material. We investigated the nature of the hadron flux to the Si Mini-Pad sensors through a full simulation and determined its effect on the sensor’s characteristics based on a beam test. The investigation showed key issues in designing a preshower detector using silicon sensors and operating under a large neutron fluence and offered valuable information on the operation of the MPC-EX detector.

Surface pattern of a Si Mini-Pad sensor for the PHENIX MPC-EX and damage caused by ionizing radiation

The Si Mini-Pad sensor is an essential component of the MPC-EX preshower detector. This detector will be integrated into the PHENIX experiment at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider. We describe the development of the surface pattern and the fabrication process of the Si Mini-Pad sensor and present a test by the low energy γ irradiation that is sensitive to the surface design.

The upgraded CMS Preshower high voltage system

In March 2012 the high voltage system of thesilicon-sensor-based CMS Preshower detector underwent a significant upgrade.In order to increase the granularity of the bias distribution lines, thenumber of power supplies was doubled and fully configurable distributionboards were developed and installed. These new boards provide much improvedflexibility in the powering, necessary to cope with the expected evolutionof the 4288 silicon sensors with radiation damage. They also providemeasurement of the ∼ 2200 bias-voltage lines that go to the detector,enabling fast identification/diagnosis of any anomalous currents andproviding detailed knowledge of the sensor current evolution over time.

Development of the preshower detector prototypes for LHCb experiment

We present results of the development and experimental study of the preshower detector prototypes for LHCb experiment in the test beam of SPS accelerator (CERN). The preshower detector consists of two identical layers of scintillator pads and a layer of lead converter in between. The light from pads is readout by means of wave-length shifting fiber coiled and glued inside a circular groove in the scintillator body. The study of prototypes allowed performing an optimal choice of the light collection and mechanical design of the preshower detector modules.

Photon–hadron discrimination with improved clustering for a preshower detector in high energy heavy ion experiments

The fuzzy c-mean clustering algorithm has been applied to the data set consisting of hits in a highly granular photon multiplicity detector installed in the ALICE experiment at the LHC. The clusters obtained using a modification of the algorithm based on the intensity of cells (called weighted fuzzy c-mean algorithm) are used as input in an artificial neural network formalism for photon–hadron discrimination. Results are discussed in terms of the photon reconstruction efficiency and the purity of photon sample and their centrality and pseudorapidity dependence at the LHC energy.

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.

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.

Commissioning of the LHCb preshower detector with cosmic rays and first LHC collisions

The LHCb calorimeter system consists of a Scintillating Pad Detector (SPD), a PreShower detector (PS) followed by electromagnetic (ECAL) and hadronic (HCAL) calorimeters. The LHCb preshower detector provides the longitudinal segmentation of the electromagnetic shower detection. It is located immediately upstream from the ECAL, with one-to-one correspondence between ECAL towers, SPD and preshower cells. The PS detector is part of the first level of the LHCb trigger system (called Level-0). It is used in conjunction with the SPD, ECAL and HCAL to search for clusters of 2 × 2 cells and to identify e, γ, π°, hadron of highest ET. This contribution discusses the requirements for the synchronisation and calibration of the PS detector, as well as the methods that were used to determine the first settings before the LHC start-up. The methods used to perform the fine synchronisation and calibration once LHC collisions were available are introduced, and the precisions that were obtained are given.

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.