High Energy Physics Detectors Research Articles

Development of a new generation of micropattern gaseous detectors for high energy physics, astrophysics and environmental applications

We have developed a cost-effective technology for manufacturing various layouts of micropattern gaseous detectors for a wide range of applications. Such devices feature resistive electrodes interfaced to a network of thin readout strips/electrodes. The following three examples of such innovative designs and their applications will be presented: a prototype of a novel double-phase liquid argon detector with a CsI photocathode immersed inside the liquid argon, a CsI-RICH detector prototype for the ALICE upgrade and GEM-like sensors for environmental safety/security applications.

Time of flight positron emission tomography towards 100ps resolution with L(Y)SO: an experimental and theoretical analysis

Scintillation crystals have a wide range of applications in detectors for high energy and medical physics. They are recquired to have not only good energy resolution, but also excellent time resolution. In medical applications, L(Y)SO crystals are commonly used for time of flight positron emission tomography (TOF-PET). This study aims at determining the experimental and theoretical limits of timing using L(Y)SO based scintillators coupled to silicon photomultipliers (SiPMs). Measurements are based on the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO and a fast oscilloscope. Using a 2 × 2 × 3 mm3 LSO:Ce codoped 0.4% Ca crystal coupled to a commercially available SiPM (Hamamatsu S10931-050P MPPC), we achieve a coincidence time resolution (CTR) of 108±5ps FWHM measured at E=511keV. We determine the influence of the data acquisition system to 27±2ps FWHM and thus negligible as compared to the CTR. This shows that L(Y)SO scintillators coupled to SiPM photodetectors are capable of achieving very good time resolution close to the desired 100ps FWHM for TOF-PET systems. To fully understand the measured values, we developed a simulation tool in MATLAB that incorporates the timing properties of the photodetector, the scintillation properties of the crystal and the light transfer within the crystal simulated by SLITRANI. The simulations are compared with measured data in order to determine their predictive power. Finally we use this model to discuss the influence of several important parameters on the time resolution like scintillation rise- and fall time and light yield, as well as single photon time resolution (SPTR) and the detection efficiency of the SiPM. In addition we find the influence of photon travel time spread in the crystal not negligible on the CTR, even for the used 2 × 2 × 3 mm3 geometry.

Monolithic pixel detectors for high energy physics

Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon have revolutionized imaging for consumer applications, but despite years of research they have not yet been widely adopted for high energy physics. Two major requirements for this application, radiation tolerance and low power consumption, require charge collection by drift for the most extreme radiation levels and an optimization of the collected signal charge over input capacitance ratio (Q/C). It is shown that monolithic detectors can achieve Q/C for low analog power consumption and even carryout the promise to practically eliminate analog power consumption, but combining sufficient Q/C, collection by drift, and integration of readout circuitry within the pixel remains a challenge. An overview is given of different approaches to address this challenge, with possible advantages and disadvantages.

Application of micro-channel cooling to the local thermal management of detectors electronics for particle physics

Micro-channel cooling is gaining considerable attention as an alternative technique for cooling of high energy physics detectors. This is of particular interest for future trackers, where large silicon surfaces are involved and the amount of material crossed by particles must be drastically reduced. Combining the versatility of standard micro-fabrication processes with the high thermal efficiency typical of micro-fluidics, it is possible to produce effective thermal management devices well adapted to different detector-specific applications. Three application cases are presented, which take into account different detector constraints and different refrigerant types: the first one being optimized for low temperature single-phase liquid flow, and the other two for evaporative cooling: one for low pressure/room temperature two-phase flow, and one for high pressure/low temperature two-phase flow.

Radiation hardness trends in new microelectronic technologies for the readout of semiconductor detectors

The semiconductor detector community is taking advantage of the most recent developments in the field of microelectronics for the design of high performance readout chips. Commercial CMOS foundries are progressing towards an aggressive scaling of the device feature size; 3D integration of two or more CMOS layers might provide an alternative or additional way to increase functional density and improve the performance of the detector system. On the other hand, advanced applications of semiconductor detectors in high energy physics, photon science and space experiments require that sensors and front-end electronics stand high levels of radiation. This paper reviews the main mechanisms that influence the radiation tolerance of nanoscale CMOS devices. This provides the basis for a discussion of the impact of radiation hardness criteria on the design and technology choices for microelectronic chips in new semiconductor detector systems.

SiPM time resolution: From single photon to saturation

The time resolution of photon detection systems is important for a wide range of applications in physics and chemistry. It impacts the quality of time-resolved spectroscopy of ultrafast processes and has a direct influence on the best achievable time resolution of time-of-flight detectors in high-energy and medical physics. For the characterization of photon detectors, it is important to measure their exact timing properties in dependence of the photon flux and the operational parameters of the photodetector and its accompanying electronics. We report on the timing of silicon photomultipliers (SiPM) as a function of their bias voltage, electronics threshold settings and the number of impinging photons. We used ultrashort laser pulses at 400nm wavelength with pulse duration below 200fs. We focus our studies on different types of SiPMs (Hamamatsu MPPC S10931-025P, S10931-050P and S10931-100P) with different SPAD sizes (25μm, 50μm and 100μm) coupled to the ultrafast discriminator amplifier NINO. For the SiPMs, an optimum in the time resolution regarding bias and threshold settings can be reached. For the 50μm type, we achieve a single photon time resolution of 80ps sigma, and for saturating photon fluxes better than 10ps sigma.

New Approaches to Improve Timing Resolution in Scintillators

The future generation of radiation detectors is more and more demanding on timing performance for a wide range of applications, such as time of flight (TOF) techniques for PET cameras and particle identification in nuclear physics and high energy physics detectors, precise event time tagging in high luminosity accelerators and a number of photonic applications based on single photon detection. A detailed analysis of the factors limiting timing resolution in scintillators is presented. Several solutions are proposed to overcome these limitations assuming the photodetector and the readout electronics are not the limiting factors. On the scintillator side both the light production and the light transport are addressed. The light production timing parameters are driven by three factors: relaxation time of hot electron-hole pairs; creation of excitons and their trapping on luminescent centers; and strength of the luminescent center transition matrix element. The opportunity to make use of Cerenkov emission and to reactivate research lines on cross-luminescence and more generally on interband luminescence, as well as on populating a high carrier density donor band is discussed. A particular emphasis is put on the possibilities offered by quantum confinement. On the side of light transport a better understanding of the statistical distribution of optical photons at the photodetector is building-up progressively. Different approaches to make use of this knowledge are proposed, such as photonic crystals, single photon counting techniques and light channeling in metamaterials.

CMS tracker performance

The Compact Muon Solenoid (CMS) experiment is a multipurpose high energy physics detector operated at the CERN Large Hadron Collider (LHC) near Geneva, Switzerland. The current status and performance of the CMS silicon tracker after 2 years of p–p collisions at s=7TeV are reviewed.

Characterizing the radiation response of Cherenkov glass detectors with isotopic sources

Cherenkov detectors are widely used for particle identification and threshold detectors in high-energy physics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we set the groundwork to evaluate large Cherenkov glass detectors for sensitivity to MeV photons through first understanding the measured response of small Cherenkov glass detectors to isotopic gamma-ray sources. Counting and pulse height measurements are acquired with reflected glass Cherenkov detectors read out with a photomultiplier tube. Simulation was used to inform our understanding of the measured results. This simulation included radioactive source decay, radiation interaction, Cherenkov light generation, optical ray tracing, and photoelectron production. Implications for the use of Cherenkov glass detectors to measure low energy gamma-ray response are discussed.

Novel Type of Aluminum-Alloy Jacketed ${\rm Nb}_{3}{\rm Sn}$ Superconductors Manufactured by Friction Stir Welding Technique

New process to compose a reacted Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting cable with aluminum-alloys has been developed by using friction stir welding (FSW) technique. The FSW joining process, which takes place in the solid phase below the melting point of the materials, has considerable advantages such as a high strength of welding zone and much lower distortion due to both small heat affects and reliable control of joining depth as compared with conventional welding method. In order to realize practical aluminum-alloy jacketed Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconductors, we have carried out elemental researches by using FSW technique. For a fabrication of aluminum-alloy jacketed Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconductor of a dimension 17 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</sup> × 4.9 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sup> a Rutherford type superconducting cable having 18 reacted Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands of diameter 1.0 mm was assembled into a set of channel and fitting-cover made of aluminum-alloy A6061-T6 with filling material indium. Then, their joining parts were connected by using the FSW technique. The measurement on critical current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) of the fabricated Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconductor achieved over 9.5 kA at 8 T, 4.26 K even after bending with a radius of 150 mm in a flatwise direction, which showed no degradation in comparison with I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values multiplied by number of strands in the cable. As the results, we succeeded in developing novel type of aluminum-alloy jacketed Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconductors manufactured by FSW technique, which have large current capacity, sufficient allowable bending strains for a coil winding and improved contact between a cable and an aluminum-alloy jacket. The developed superconductors will be applicable to react-and-wind superconducting magnets having very large current at high magnetic field such as nuclear fusion reactors and detectors for high energy physics of the next generation.

Achieving sub electron noise in CCD systems by means of digital filtering techniques that lower 1/f pixel correlated noise

Scientific CCDs designed in thick high resistivity silicon (Si) are excellent detectors for astronomy, high energy and nuclear physics, and instrumentation. Many applications can benefit from CCDs ultra low noise readout systems. The present work shows how sub electron noise CCD images can be achieved using digital signal processing techniques. These techniques allow 0.4 electrons of noise at readout bandwidths of up to 10 Kpixels per second while keeping the full CCD spatial resolution and signal dynamic range.

EMC issues in CMS infrastructure

The electronic systems of modern high-energy physics detectors are generally built with electromagnetic compatibility issues as an important part of the requirements driving the design of the detector. The CMS experiment at CERN has an appreciable amount of electronic infrastructure not usually found in previous generations of high-energy physics detectors. Over more than a year of CMS running, we have had the opportunity to observe several instances of unexpected interactions with infrastructure electronics. This paper will examine some mechanisms and consequences of these interactions, as well as considering the coordination of infrastructure and detector electronics design.

One Year of FOS Measurements in CMS Experiment at CERN

Results are presented on the activity carried out by our research group, in collaboration with the SME Optosmart s.r.l. (an Italian spin-off company), on the application of Fiber Optic Sensor (FOS) techniques to monitor high-energy physics (HEP) detectors. Assuming that Fiber Bragg Grating sensors (FBGs) radiation hardness has been deeply studied for other field of application, we have applied the FBG technology to the HEP research domain. We present here the experimental evidences of the solid possibility to use such a class of sensors also in HEP detector very complex environmental side conditions. In particular we present more than one year data results of FBG measurements in the Compact Muon Solenoid (CMS) experiment set up at the CERN, where we have monitored temperatures (within CMS core) and strains in different locations by using FBG sensors during the detector operation with the Large Hadron Collider (LHC) collisions and high magnetic field. FOS data and FOS readout system stability and reliability is demonstrated, with continuous 24/24 h 7/7d data taking under severe and complex side conditions.

Microfluidic cooling for detectors and electronics

Micro-channel cooling is gaining considerable attention as an alternative technique for cooling of high energy physics detectors and front-end electronics. This technology is being evaluated for future tracking devices, where material budget limitations are a major concern. It is currently under investigation as an option for the cooling of the NA62 Gigatracker silicon pixel detector, where a micro-fabricated silicon cooling plate would stand directly in the beam. Other possible applications are also being studied in the context of LHC detectors upgrades. In this paper, the current status of this R&D at CERN is presented.

Application of Detectors in High Energy Physics to Medical Physics

Application of Detectors in High Energy Physics to Medical Physics

Silicon photomultipliers for high energy physics detectors

In this paper I want to review the current status of development of multi-pixel silicon-based avalanche photo-diodes operated in Geiger mode, also known as Silicon Photomultipliers (SiPM). Particular emphasis is given to the application of this type of photo-sensors in high energy physics detectors.

Development and Performance Verification of the GANDALF High-Resolution Transient Recorder System

With present-day detectors in high energy physics one often faces fast analog pulses of a few nanoseconds length which cover large dynamic ranges. In many experiments both amplitude and timing information have to be measured with high accuracy. Additionally, the data rate per readout channel can reach several MHz, which leads to high demands on the separation of pile-up pulses. For an upgrade of the COMPASS experiment at CERN we have designed the GANDALF transient recorder with a resolution of 12 bit@1 GS/s and an analog bandwidth of 500 MHz. Signals are digitized with high precision and processed by fast algorithms to extract pulse arrival times and amplitudes in real-time and to generate trigger signals for the experiment. With up to 16 analog channels, deep memories and a high data rate interface, this 6U-VME64x/VXS module is not only a dead-time free digitization unit but also has huge numerical capabilities provided by the implementation of a Virtex5-SXT FPGA. Fast algorithms implemented in the FPGA may be used to disentangle possible pile-up pulses and determine timing information from sampled pulse shapes with a time resolution better than 50 ps.

Low-cost bump bonding activities at CERN

Conventional bumping processes used in the fabrication of hybrid pixel detectors for High Energy Physics (HEP) experiments use electroplating for Under Bump Metallization (UBM) and solder bump deposition. This process is laborious, involves time consuming photolithography and can only be performed using whole wafers. Electroplating has been found to be expensive when used for the low volumes which are typical of HEP experiments. In the low-cost bump bonding development work, electroless deposition technology of UBM is studied as an alternative to the electroplating process in the bump size / pitch window beginning from 20 μm / 50 μm. Electroless UBM deposition used in combination with solder transfer techniques has the potential to significantly lower the cost of wafer bumping without requiring increased wafer volumes.A test vehicle design of sensor and readout chip, having daisy chains and Kelvin bump structures, was created to characterize the flip chip process with electroless UBM. Two batches of test vehicle wafers were manufactured with different bump pad metallization. Batch #1 had AlSi(1%) metallization, which is similar to the one used on sensor wafers, and Batch #2 had AlSi(2%)Cu(1%) metallization, which is very similar to the one used on readout wafers. Electroless UBMs were deposited on both wafer batches. In addition, electroplated Ni UBM and SnPb solder bumps were grown on the test sensor wafers. Test assemblies were made by flip chip bonding the solder-bumped test sensors against the test readout chips with electroless UBMs. Electrical yields and individual joint resistances were measured from assemblies, and the results were compared to a well known reference technique based on electroplated solder bumps structures on both chips. The electroless UBMs deposited on AlSi(2%)Cu(1%) metallization showed excellent electrical yields and small tolerances in individual joint resistance. The results from the UBMs deposited on AlSi(1%) metallization were non-uniform and closer inspection revealed micro cracks at aluminum — electroless nickel interface. UBM deposition was also done for Timepix wafers and solder ball placement process was prototyped with 40 μm balls.

Data Preservation in High Energy Physics – why, how and when?

Long-term preservation of data and software of large experiments and detectors in high energy physics is of utmost importance to secure the heritage of (mostly unique) data and to allow advanced physics (re-)analyses at later times. Summarising the work of an international study group, motivation, use cases and technical details are given for an organised effort to secure and enable future use of past, present and future experimental data. As a practical use case and motivation, the revival of JADE data and the corresponding latest results on measuring αs in NNLO QCD are reviewed.

Overview on calorimetry

In this paper I want to review the state of the art of calorimeter developments. I will focus on innovative solutions in calorimetry at the technology frontier and I will favor calorimeters for High Energy Physics detectors. The field in which calorimeters find their application is so broad that this short review does not do justice to all ongoing projects. Instead, this paper shall be considered as a collection of currently hot topics on the subject.