Shashlik Calorimeter Research Articles

Readout studies for the HIKE main electromagnetic calorimeter

The High-Intensity Kaon Experiment (HIKE) is a proposed future kaon experiment designed for the CERN SPS accelerator. To cope with a planned increase of beam intensity by a factor of 4 with respect to the current NA62 experiment, the new Main Electromagnetic Calorimeter (MEC) has to provide a similar improvement in time resolution over the current Liquid Krypton calorimeter, down to ≈100ps for a 40GeV photon, while maintaining a comparable energy and spatial resolution. To achieve these goals, the planned detector consists of a shashlik calorimeter paired with high-resolution analog to digital converter for both energy deposit and arrival time estimates, operating at fast sample rates (∼1GHz).This contribution describes a prototype of the readout system using commercial “off-the-shelf” boards. In particular, we focused on feature extraction and tested it using a pulse generator. We included a data readout logic based on the TCP/IP protocol allows for easy deployment in beam tests.

First characterization of a novel grain calorimeter: the GRAiNITA prototype

A novel type of calorimeter based on grains of inorganic scintillating crystal readout by wave length shifting fibers is proposed. The concept and main features as well as the prototype design are introduced and the first results obtained using cosmic rays are presented. The number of photo-electrons generated by cosmic rays muons in the prototype detector is estimated to be of the order of 10000 photo-electrons per GeV, validating the concept of this next-generation shashlik calorimeter.

Silicon Photomultipliers for the decay tunnel instrumentation of the ENUBET neutrino beam

The goal of the ENUBET project is to demonstrate that a precision of ∼1% on measurement of the absolute neutrino cross section at GeV scale can be achieved by monitoring the positron production in the decay tunnel coming from the three-body semileptonic decays of kaons. The baseline option for the tunnel instrumentation employs a fine-grained shashlik calorimeter with a 4.3 X0 longitudinal segmentation to separate positrons and pions coming from other decay modes of kaons. The system is complemented by rings of plastic scintillator doublets below the calorimeter acting as a photon veto to suppress the π0 background and to provide timing informations. SiPMs instrumenting the detector will be exposed to sizeble amounts of neutrons arising in hadronic showers. In order to reproduce such a working environment, SiPMs with different cell size (from 12 to 20 μm) were irradiated at the INFN-LNL CN Van Der Graaf with neutron fluences up to 2×1011 n/cm2 (1 MeV-eq.). The exposed light sensors were characterized in terms of I–V curves at different irradiation levels, and their response tested by exposing a prototype on beam at CERN. In this contribution we will report the results of the described tests on SiPMs, together with the advances in their integration with the ENUBET detectors.

Polysiloxane-based scintillators for shashlik calorimeters

We present the first application of polysiloxane-based scintillators as active medium in a shashlik sampling calorimeter. These results were obtained from a testbeam campaign of a ∼6×6×45 cm3 (13 X0 depth) prototype. A Wavelength Shifting fiber array of 36 elements runs perpendicularly to the stack of iron (15 mm) and polysiloxane scintillator (15 mm) tiles with a density of about one over cm2. Unlike shashlik calorimeters based on plastic organic scintillators, here fibers are optically matched with the scintillator without any intermediate air gap. The prototype features a compact light readout based on Silicon Photo-Multipliers embedded in the bulk of the detector. The detector was tested with electrons, pions and muons with energies ranging from 1 to 7 GeV at the CERN-PS. This solution offers a highly radiation hard detector to instrument the decay region of a neutrino beam, providing an event-by-event measurement of high-angle decay products associated with neutrino production (ENUBET, Enhanced NeUtrino BEams from kaon Tagging, ERC project). The results in terms of light yield, uniformity and energy resolution, are compared to a similar calorimeter built with ordinary plastic scintillators.

Shashlik calorimeters for the ENUBET tagged neutrino beam

Shashlik calorimeters equipped with a compact readout based on Silicon PhotoMultipliers can be longitudinally segmented by directly coupling the WLS fibers with the photosensors thus embedding the readout in the bulk of the calorimeter. Results on energy resolution and particle identification for such calorimeters are presented. The SiPMs for the readout have also been characterized after being exposed to neutron fluences up to 2×1011 n/cm2 (1 MeV eq.). Alternative options for the active material were also investigated; we studied in particular polysiloxane as a substitute for plastic scintillator.

Shashlik calorimeters: Novel compact prototypes for the ENUBET experiment

We summarize in this paper the detector R&D performed in the framework of the ERC ENUBET Project. We discuss in particular the latest results on longitudinally segmented shashlik calorimeters and the first HEP application of polysiloxane-based scintillators.

Testbeam performance of a shashlik calorimeter with fine-grained longitudinal segmentation

An iron- plastic-scintillator shashlik calorimeter with a 4.3 X0 longitudinal segmentation was tested in November 2016 at the CERN East Area facility with charged particles up to 5 GeV . The performance of this detector in terms of electron energy resolution, linearity, response to muons and hadron showers are presented in this paper and compared with simulation. Such a fine-grained longitudinal segmentation is achieved using a very compact light readout system developed by the SCENTT and ENUBET Collaborations, which is based on fiber-SiPM coupling boards embedded in the bulk of the detector. We demonstrate that this system fulfills the requirements for neutrino physics applications and discuss performance and additional improvements.

A Very Compact Crystal Shashlik Electromagnetic Calorimeter for Future HEP Experiments

A very compact crystal based shashlik calorimeter is proposed for future HEP experiments in an extreme harsh radiation environment, such as the proposed HL-LHC. Thin crystal plates are used as the sensitive medium to reduce the light path length and thus the radiation damage effects and the calorimeter cost. A design of such a calorimeter uses tungsten as absorber, LYSO crystals as active medium, and liquid scintillator filled quartz capillaries as WLS to transport scintillating light to photodetectors. Initial calorimeter design and performance of prototype modules are presented. Possible optimizations are discussed.

Simulation study of energy resolution, position resolution and >π0-γ separation of a sampling electromagnetic calorimeter at high energies

A simulation study of energy resolution, position resolution, and π0-γ separation using multivariate methods of a sampling calorimeter is presented. As a realistic example, the geometry of the calorimeter is taken from the design geometry of the Shashlik calorimeter which was considered as a candidate for CMS endcap for the phase II of LHC running. The methods proposed in this paper can be easily adapted to various geometrical layouts of a sampling calorimeter. Energy resolution is studied for different layouts and different absorber-scintillator combinations of the Shashlik detector. It is shown that a boosted decision tree using fine grained information of the calorimeter can perform three times better than a cut-based method for separation of π0 from γ over a large energy range of 20 GeV–200 GeV.

Shashlik Calorimeters With Embedded SiPMs for Longitudinal Segmentation

Effective longitudinal segmentation of shashlik calorimeters can be achieved taking advantage of the compactness and reliability of silicon photomultipliers. These photosensors can be embedded in the bulk of the calorimeter and are employed to design very compact shashlik modules that sample electromagnetic and hadronic showers every few radiation lengths. In this paper, we discuss the performance of a calorimeter made up of 12 such modules and able to sample showers every $\sim 4X_{0}$ . In summer 2016, this prototype has been exposed to electrons, muons, and hadrons at CERN PS (East Area T9 beamline). The performances in terms of energy resolution, linearity, response to minimum ionizing particles, and reconstruction of the shower profile are discussed.

ENUBET: Enhanced NeUtrino BEams from kaon Tagging

A reduction of the neutrino flux uncertainty by one order of magnitude in conventional neutrino beams can be achieved monitoring the positron production in the decay tunnel originating from the Ke3 decays of charged kaons. This novel approach will be developed in the framework of the ERC ENUBET Project. In this talk we present the aims of the project and the ongoing R&D for the instrumentation of the decay tunnel. In particular, we describe a specialized shashlik calorimeter (iron-scintillator) with a compact readout based on small-area silicon photo multipliers that allows for a very effective longitudinal segmentation of the detector to enhance electron/hadron separation. The expected performance of the detector estimated from a full GEANT4 simulation of the neutrino decay tunnel are presented. We also discuss preliminary results on a prototype composed by 12 ultra compact modules exposed to pions and electrons at CERN-PS.

A compact light readout system for longitudinally segmented shashlik calorimeters

The longitudinal segmentation of shashlik calorimeters is challenged by dead zones and non-uniformities introduced by the light collection and readout system. This limitation can be overcome by direct fiber–photosensor coupling, avoiding routing and bundling of the wavelength shifter fibers and embedding ultra-compact photosensors (SiPMs) in the bulk of the calorimeter. We present the first experimental test of this readout scheme performed at the CERN PS-T9 beamline in 2015 with negative particles in the 1–5GeV energy range. In this paper, we demonstrate that the scheme does not compromise the energy resolution and linearity compared with standard light collection and readout systems. In addition, we study the performance of the calorimeter for partially contained charged hadrons to assess the e/π separation capability and the response of the photosensors to direct ionization.

Longitudinally segmented shashlik calorimeters with SiPM readout

The goal of the INFN SCENTT R&D project is to develop the calorimeter technologies for the instrumentation of decay tunnels in conventional neutrino beams. This instrumentation is required to achieve a substantial improvement in the uncertainty on neutrino fluxes for the next generation cross section experiments. In particular, we are designing a positron tagger based on purely calorimetric techniques that is able to measure the rate and the spectrum of the positrons produced in the K+→e+π0νe decay. The νe flux is inferred from the positron rate in the decay tunnel. Considering the large dimensions of the tagger, the most cost effective technology is based on small modules of Fe/Scintillator shashlik calorimeters, with adequate segmentation and energy resolution to efficiently tag the positrons over the charged pion background. This contribution presents preliminary results obtained with two shashlik calorimeter prototypes readout with an array of Silicon PhotoMultipliers and tested at the CERN PS-T9 beamline.

Monitoring LSO/LYSO Crystal Calorimeters

LSO/LYSO crystals were chosen by the SuperB, Mu2e and COMET experiments to construct total absorption electromagnetic calorimeters. They were also proposed as the active medium for a Shashlik calorimeter which was one of the two options proposed for the CMS forward calorimeter upgrade at the proposed HL-LHC. Because of the severe radiation environment expected at the HL-LHC, precision light monitoring is crucial for keeping excellent energy resolution promised by LYSO crystals. This paper discusses the wavelength choice for monitoring LYSO based crystal calorimeters. $\gamma $ -ray induced absorption and light output loss were measured for 20 cm long crystals from five different vendors. Monitoring sensitivity and divergence are analyzed. Two approaches using excitation and emission light and their practical implementations in a beam test at Fermilab are discussed. The response of an LYSO/W Shashlik calorimeter cell after a $\gamma $ -ray irradiation of 90 Mrad is also presented.

Precision Timing Calorimeter for High Energy Physics

We present studies on the performance and characterization of the time resolution of LYSO-based calorimeters. Results for an LYSO sampling calorimeter and an LYSO-tungsten Shashlik calorimeter are presented. We demonstrate that a time resolution of 30 ps is achievable for the LYSO sampling calorimeter. We discuss timing calorimetry as a tool for mitigating the effects due to the large number of simultaneous interactions in the high luminosity environment foreseen for the Large Hadron Collider.

A new-concept calorimeter for future neutrino beams based on Kaon tagging

Neutrino cross-section measurements are an essential requirement for the next generation of neutrino oscillation experiments and they are presently limited by uncertainties on neutrino fluxes. In [1] we propose to instrument a neutrino decay tunnel to detect large angle positrons and tag the three-body semileptonic K+→e+π0νe decays. In such a facility the absolute electron neutrino flux could be determined with unprecedented precision (O(1%)). An e+/π+ separation capability of about 2% as well as a high e+ efficiency is required for a diffuse particle source over a length of several tens of meters. Additional constraints, due to the harsh beam environment, involve radiation hardness and fast response. For this purpose we propose a specialized shashlik calorimeter (copper-scintillator) with a compact readout based on small-area Silicon PhotoMultipliers coupled to WLS fibers. The setup would allow an effective longitudinal segmentation for electron/hadron separation, reducing the dead zones introduced by fiber bundling. Detailed Monte Carlo simulations are in progress. The construction of a small prototype and exposures to pion and electron beams are foreseen.

Upgrade of the LHCb ECAL monitoring system

The LHCb ECAL is a shashlik calorimeter of 6016 cells, covering 7.68×6.24 m2 area. To monitor the readout chain of each ECAL cell, the LHCb ECAL is equipped with a LED based monitoring system. During the LHC Run I (2009-2012) it was found that the precision of the monitoring suffers from the radiation degradation of transparency of polystyrene clear fibers used to transport the LED light to the ECAL photomultipliers. In order to improve the performance of the monitoring system, and especially in view of significant increase of LHCb working luminosity foreseen after 2018, the present plastic fibers have been replaced by radiation hard quartz fibers. The performance of the old LHCb ECAL monitoring system during LHC Run I and the design of the upgraded system are discussed here.

Characterization of a DAQ system for the readout of a SiPM based shashlik calorimeter

Silicon PhotoMultipliers (SiPMs) are a recently developed type of silicon photodetector characterized by high gain and insensitivity to magnetic fields, which make them a suitable detector for the next generation high energy and space physics experiments. This paper presents the performance of a readout system for SiPMs based on the MAROC3 ASIC. The ASIC consists of 64 channels working in parallel, each one with a variable gain pre-amplifier, a tunable slow shaper with a sample & hold circuit for the analog readout and a tunable fast shaper for the digital one. In the tests described in this paper, only the analog part of the ASIC has been used. A frontend board based on the MAROC3 ASIC has been tested at CERN coupled to a scintillator-lead shashlik calorimeter, readout with 36 large area SiPMs. The performance of the system has been characterized in terms of linearity and energy resolution on the CERN PS-T9 and SPS-H2 beamlines, using different configurations of the ASIC parameters.

A shashlik calorimeter readout with silicon photomultipliers with no amplification of the output signal

Silicon PhotoMultipliers are silicon photodetectors that can be used to replace the photomultiplier tubes in many experimental situations. In this article we describe the performance of SiPMs as a readout system of a shashlik calorimeter composed of 70 11.5x11.5 cm2 4 mm thick tiles of scintillator and 69 11.5x11.5 cm2 1.5 mm thick tiles of lead for a total of ∼ 19 radiation lengths; the light is collected by 144 1.2 mm wave-length-shifter (WLS) fibers grouped in bundles of nine for a total of 16 channels. The SiPMs are manufactured by FBK-irst and have a sensitive area of 9 mm2. The calorimeter has been tested at CERN using both a low (PS T9 beamline) and high (SPS H4 beamline) energy beam in 2010.

Silicon Photomultipliers as a Readout System for a Scintillator-Lead Shashlik Calorimeter

Silicon photomultipliers are silicon devices that in recent times have been proposed as candidates for the replacement of photomultiplier tubes in many experimental situations. In this article we describe the performance of SiPMs as a readout system of a shashlik calorimeter composed of 41 8×8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 3.27-mm-thick tiles of scintillator and 40 8×8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 3.27-mm-thick tiles of lead, for a total of ~24 radiation lengths; the light is collected by 64 0.8-mm wave-length-shifter (WLS) fibers grouped in bundles of four for, a total of 16 channels. The SiPMs are manufactured by FBK-irst and have a sensitive area of 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The calorimeter has been tested at CERN using both a low (PS T10 beamline) and high (SPS H4 beamline) energy beam during the summer 2009 data taking.