Forward Electromagnetic Calorimeter Research Articles

Development of indigenous silicon detector and readout electronics for forward electromagnetic calorimeter prototypes

Development of indigenous silicon detector and readout electronics for forward electromagnetic calorimeter prototypes

FoCal: A highly granular digital calorimeter

This contribution discusses the recent progress in the development of a highly granular digital electromagnetic calorimeter proposed as an upgrade to the ALICE detector. This forward electromagnetic calorimeter (FoCal) must be able to discriminate decay photons from direct photons at very high energy, which requires extremely high granularity and a small Molière radius. A dedicated R&D program is ongoing to develop the technology needed for such a high-granularity device. Within this program we have constructed a prototype of a digital electromagnetic calorimeter based on CMOS monolithic active pixel sensors (MAPS). This prototype has demonstrated the unique capabilities of such a highly granular digital calorimeter, providing unprecedented shower profile measurements and good linearity and energy resolution. The prototype was based on the MIMOSA chip, which is however not fast enough for application in a full detector at the LHC. As a next step, the ALPIDE chip developed for the ALICE Inner Tracker Upgrade is being investigated for performance with high occupancy. This contribution presents results from the current prototype, the performance of the ALPIDE and plans for the next prototype.

Research on cluster reconstruction algorithm for the STAR forward electromagnetic calorimeter

The Forward Meson Spectrometer, FMS, is a forward electromagnetic calorimeter at the STAR detector at RHIC, covering pseudorapidity from 2.6 to 4.0. It is an electromagnetic calorimeter comprised of two different types of 1264 lead-glass cells where the two types vary in both composition and size. The FMS was built primarily to unravel the novel spin effects seen in transversely polarized proton collisions. These effects relate to the spin-orbit correlation of the partons in the proton to the spin of the proton, which is a consequence of the confined motion of partons in nucleons. The reconstruction of neutral pions in the FMS is essential to study these effects. The gain calibration of the FMS is solely based on the reconstruction of the invariant mass of neutral pions at a fixed energy – because there is no tracker or hadronic calorimeter around – which poses the complication that the calibration gets intertwined with the reconstruction algorithm. Also, in order to cover the kinematic region of interest, the FMS needs to measure pion energies as high as 80 GeV at pp collisions with center-of-mass energies of 200 and 500 GeV. It was found that there was a strong correlation between the reconstructed neutral pion mass and its energy due to a combination of biases in the photon finding, namely the energy and the opening angle of the decay photons. The impact of the non-linear response of the lead-glass on the energy-scale was verified in detailed simulations of the light attenuation in the lead-glass and it was found that a correction function could be established. The fitting of the electromagnetic shower shape was modified to include non-zero incident angles and non-zero vertex positions. The reconstruction algorithm was optimized for clusters with two showers, especially when the separation of the two photons nears the physical limit in terms of the cell sizes. This article will present details of all these improvements and their impact on the reconstruction of neutral pions with the FMS.

A Low Noise Front End for the Belle II Forward Electromagnetic Calorimeter Upgrade

The Belle II experiment will operate at the SuperKEKB e+ e− collider, designed to reach a top luminosity of $8 \times 10^{35}$ at the $\Upsilon $ (4s) resonance. The high background environment of the accelerator poses serious challenges to the design of the detector. In particular, the Belle II collaboration is developing an ambitious upgrade program that involves the forward electromagnetic calorimeter. We will use pure CsI crystals, since they have less scintillation time but unfortunately much lower light yield. The electromagnetic calorimeter upgrade is subject to the same detector constraints as the first design; an intense research and development program on photon-detectors and front-end electronics has been initiated by the Italian collaboration. Our preliminary results show that a readout chain using avalanche photodiodes (APDs) to match the detector constraints and a dedicated front-end card for the readout meet the Belle II collaboration requirements. In this paper, we will show the experimental setup and detail the main characteristics of the read-out and power distribution system since the front-end card hosts both a low noise preamplifier and a power regulator to set the single APD bias voltage. The main HV module has been developed for this purpose to deliver a low noise power distribution to the front-end cards. All the relevant parameters of the front-end system can be set and monitored via Ethernet using the Experimental Physics and Industrial Control System. Slow control and monitoring functions in Belle II are performed by a dedicated hardware. The platform has been designed as an uP-based service-oriented platform, capable to offer an integrated solution for all the needs of data acquisition, analysis, and network functions.

Simulation of π0-γ Separation Study for Proposed CMS Forward Electromagnetic Calorimeter

The Forward Electromagnetic Calorimeter of the CMS detector is going to be upgraded in the high luminosity running as the energy of the present Electromagnetic Calorimeter (PbWO4) will degrade in the high luminosity (luminosity 1034cm-2s-1) running due to extensive radiation (hadron flux 1013neutrons cm,-2). Shashlik Electromagnetic Calorimeter which consists of alternate layers of 1.5 mm LYSO(Ce) crystal plates and 2.5 mm Tungsten absorbers, was a proposal for high luminosity running. One of the performance points for any electromagnetic calorimeter is the ability to separate π0 s from true photons, since final states with photons are a clean and one of the most important final states in proton-proton collisions at the LHC. The objective of this project is to study the possibility of π0 and γ separation in the Shashlik detector using Multivariate Analysis (MVA) technique.

Highly granular digital electromagnetic Calorimeter with MAPS

A highly granular digital electromagnetic calorimeter has been built using MAPS/MIMOSA23 with 30 micron pixel size to prove the feasibility of the proposed Forward electromagnetic Calorimeter (FoCal) as a possible upgrade of the ALICE apparatus. The physics motivations of such a project are presented together with the calorimeter performance in several test beam campaigns. We show the energy resolution, longitudinal and lateral profile and compare the experimental values with the simulations in the energy range from 2 to 200 GeV.

Development of the FoCal-E PAD detector and its electronics for the ALICE experiment at the LHC

In order to study the initial state of high-energy heavy-ion collisions, a forward calorimeter as an upgrade to the ALICE experiment is in the planning stage. The first beam test of the forward electro-magnetic calorimeter (FoCal-E) prototype was carried out in 2014 at the CERN PS and SPS accelerators. With the aim of reading out a signal from the low-granularity silicon pad sensors of FoCal-E, electronic circuits such as a temperature monitor, a trigger-signal converting-circuit, a trigger-signal processor, an independent regulated power circuit and an isolated high-voltage generator were developed. The electric noise problem was solved by means of both the power circuit and the high-voltage generator, and the signal was successfully read out.

Small- x physics with the ALICE experiment at the CERN-LHC

High energy p–p, p–Pb and Pb–Pb collisions at the CERN-LHC offer unprecedented opportunities for studying wide variety of physics at small Bjorken- x. Here we discuss capabilities of the ALICE experiment at the CERN-LHC for probing small- x QCD physics. A new forward electromagnetic calorimeter is being proposed as an ALICE upgrade to explore the small- x region in detail.

The Fermilab E760 forward electromagnetic calorimeter

Fermilab experiment E760 will perform precision measurements of charmonium masses and widths, as well as search for the yet unconfirmed η′ c, 1P 1, and 1,3D 2 states, using a hydrogen gas jet target in the Antiproton Accumulator. The E760 detector includes a forward electromagnetic calorimeter which has been calibrated with electron beams from 0.06 to 3 GeV, as well as π 0's produced in proton-proton collisions in an engineering run in the Accumulator. Results of these tests and other features of the calorimeter are presented.

The multiplexed ADC system and the FASTBUS readout for the DELPHI forward electromagnetic calorimeter

Two modules will be used to digitize and store the signals of the DELPHI Forward Electromagnetic Calorimeter (FEMC): these are the ADC card and the Optical Receiver with Front-End Buffer unit (OFB). A description of these modules and their performance are presented.

Transverse profile of electron showers in a lead-glass calorimeter

Abstract As a part of a large experimental program aiming to produce high quality calibration data for the Forward ElectroMagnetic Calorimeter (FEMC) of the DELPHI detector at LEP, special runs were devoted to the study of the transverse profile of electromagnetic showers in lead glass. Results of this study are presented.

Parallel arrays of digital signal processors as central decision elements for upper level triggers in high energy physics experiments

For tracking devices and calorimeters, the conflicting trends toward higher luminosity and improved background rejection have prompted the use of a hierarchical, multilevel trigger logic: the upper levels are usually devoted to 'physical' background rejection and event flagging, as opposed to the lower level logic, mostly dealing with 'dull' background at high rate. For the higher trigger levels, depending on the different machine and detector configurations, it is sometimes possible to design the 'detector data box' as a programmable device, with increased flexibility and efficiency, and to use large arrays of digital signal processors working in parallel, giving excellent data throughputs inexpensively, provided that fast and efficient software algorithms can be implemented. A flexible and powerful scheme of this type is described, for two different experiments: the forward electromagnetic calorimeter of the DELPHI experiments at LEP (CERN), and the straw tube chamber of the E760 experiment at the antiproton accumulator at Fermilab.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A low noise, large dynamic range pulse amplifier

We have developped a low noise, high dynamic range low cost amplifier. This amplifier will equip the shower position detector (current division readout) and the photomultipliers of the forward electromagnetic calorimeter in the UA1 experiment (CERN pp collider).