Advanced Particle Detector Laboratory

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1. High-Granularity Calorimeter (HGCAL)

HGCAL is one of the most ambitious detector projects undertaken, due to the combination of extremely high readout and trigger granularity,coupled with the harsh radiation environment of the CMS endcaps during HL-LHC operation. Two radiation-tolerant materials have been selected: silicon in the high-radiation region and plastic scintillator tiles in the less harsh regions. To mitigate the effects of radiation damage,the silicon sensors must be cooled to about –32°C, which also allows the use of on-tile silicon photomultipliers for the scintillator readout.

HGCAL has around 6.5 million detector channels, divided into 50 layers. The first 28 layers form the electromagnetic section, which is based on hexagonal silicon sensors (maximising the useable surface of 8" circular silicon wafers) divided into hexagonal cells. The sensors are sandwiched between high-density copper-tungsten alloy baseplates on one side and printed circuit boards containing the front-end electronics on the other, and the resulting hexagonal modules are mounted on either side of CO2-cooled copper plates. The following eight layers are similar, forming the front part of the hadronic section of HGCAL, but are single-sided and use a lighter baseplate, while the final 12 layers incorporate both silicon modules and scintillator tiles. The use of both detector technologies optimises the overall cost of the HGCAL whilst maintaining excellent long-term performance.

Prototype development began in 2016, and hexagonal silicon sensors have been built into modules to evaluate the feasibility of the overall design and to study the performance in beams at Fermilab, DESY and CERN. Results from these beam tests compare very well with simulations. Thanks to HGCAL's readout/triggering granularity and timing resolution for showers, the expected performance in terms of energy resolution, particle identification and triggering are all comparable to the present CMS endcap calorimeters – even in the presence of 200 pileup events and after the full radiation exposure expected at HL-LHC. The project has now moved to the final design and prototyping phase, with construction due to start in a couple of years.

The high-granularity calorimeter (HGCAL) is a major upgrade of CMS, and is necessary to maintain excellent calorimetric performance in the endcaps during HL-LHC operations.

Machine Learning for Quality Control

The wire-bond between the silicon sensor and the circuit board is the primary mode to collect the signal in a silicon detector. Hence, the clean and unbroken bond is one of the vital demands in the silicon module during the construction. Each of these bond holes needs to be inspected at least three times during the assembly i.e., before and after wire-bonding, and after encapsulation. Depending on the size of the detector, the number of the holes to be quality checked are at the order of million. The small dimension of the bond holes and the thickness of wires poses additional challenge in quality control. As manually checking each hole would be cumbersome and prone to human errors, we have been exploring and testing the deep learning-based computer vision to automate this quality control (QC). In particular, the image classification technique with the convolutional neural networks (CNN) has been utilized to identify the quality of the bond hole. In addition, we have been implementing the transfer learning and image segmentation techniques in this classification task. Can we transfer this learning outcome to other projects as well? This is one of the goals of our feasibility study. 

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2. Silicon Detector R&D

Silicon is ubiquitous. It is the most common, versatile, and pure material in the electronics industry, and it lends itself to myriad applications in particle physics detectors. One of our main activities involves using a large quantity of planar silicon sensors (600 m2) in the high granularity calorimeter (HGCAL) in the Compact Muon Solenoid (CMS) at the High Luminosity Large Hadron Collider (HL-LHC). When completed in 2026, the integrated neutron fluences will exceed 1016 neutrons per cm2 for the HGCAL, so it is absolutely critical that we understand the processes that are at work in radiation damage and are able to simulate and quantitatively predict diminishing detector performance under irradiation for any application. We have been investigating many different test structures and sensors and characterizing their properties. Some of the results are in our papers

• Modeling of surface-state induced inter-electrode isolation of n-on-p devices in mixed-field and gamma-irradiation environments, N. Akchurin and T. Peltola, Submitted to NIM A; arXiv:2407.18415 [physics.ins-det] (2024)
• A method to observe field-region oxide charge and inter-electrode isolation from CV-characteristics of n-on-p devices,  T. Abdilov, N. Akchurin, C. Carty, Y. Kazhykarim, V. Kuryatkov, T. Peltola, A. Wade, JINST 19 P09010, arXiv:2402.04365 [physics.ins-det] (2024)
• Neutron irradiation and electrical characterisation of the first 8" silicon pad sensor prototypes for the CMS calorimeter endcap upgrade, B. Acar et al, JINST 8, P08024 (2023)
• Modeling of Surface Damage at the Si/SiO2-interface of Irradiated MOS-capacitors, N. Akchurin, Y. Kazhykarim, V. Kuryatkov, T. Mengke, T. Peltola, et al, JINST 18 P08001 (2023)
• Simulations of Silicon Radiation Detectors for High Energy Physics Experiments, B. Nachman, T. Peltola. Contributing authors: P. Asenov, M. Bomben, R. Lipton, F. Moscatelli, E. A. Narayanan, F. R. Palomo, D. Passeri, S. Seidel, X. Shi,   J. Sonneveld, arXiv:2203.06216, March 2022
• Charge Collection and Electrical Characterization of Neutron Irradiated Silicon Pad Detector for the CMS High Granularity Calorimeter, JINST 15 (2020) P09031

Our team continues to investigate new types of silicon detectors for future applications through TCAD simulations, sample fabrication, and characterization.

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3. LIMYRA - Muon Tomography

Tomography is an imaging technique to reveal the internal structure of objects using microwaves, x-rays, or particle beams. It is widely used in diverse fields such as medicine, biology, archaeology, geology, material science, manufacturing, and homeland security. Muon tomography, on the other hand, makes use of cosmic muons as the probing beam. Because muons, due to their weak interactions with matter, are able to penetrate massive objects, they are ideal for imaging the internal structures of large objects, such as Egyptian pyramids, volcanos, nuclear reactors, cargo containers, or similarly sizable and dense structures.

TTU's muon tomography project started in 2016 as an undergraduate research project. See a Symmetry article on our work.  Since then, twelve students from the departments of Physics and Astronomy, Mathematics, Electrical and Computer Engineering, Mechanical Engineering, and Computer Science have worked on the design, construction, and operation of the first prototype detector. They brought expertise from their respective departments and completed the construction of our first prototype earlier this year.

The Team Members:   

• Aashish Gupta (Physics, BS 2018, now in a graduate program in medical physics)
• Hunter Cymes (ME, BS 2018, now in private industry)
• William Milestone (Physics, BS 2019, now in graduate program in EE at TTU)
• Jake Noltensmeyer (Physics, BS 2020, now in graduate program in physics at New Mexico)
• Raul Perez (Physics, BS 2020, now in graduate program in EE at TTU)
• Sadman Ahmed Shanto (Applied Physics and Math, BS 2021, now in graduate program in Quantum
• Computing at USC)
• Samuel Cano (Physics, BS 2021, now in graduate program in Space and Planetary Sciences at UArk)
• Cristobal Moreno (Physics, BS 2021)
• Mohammad Moosaje (Applied Physics, BS 2021)
• Victor Bradley (Physics, BS 2022)
• Madison Howard (Physics & Math, BS 2022)
• Clive Binu (Astrophysics, BS 2022)
• Gabriel Chiselenco (Physics, BS 2023)

The imaging test started in August 2019 and produced low resolution images of a 30-feet diameter water tank at the Reese Research Center. This prototype is limited to ~20 mradians spatial resolution.  Our second prototype is in the designing stage.

Our next project consists of scanning Queen Maeve's cairn in Ireland. The tomb is suspected to consist of a chamber and a passage which are covered by a mound of rocks. The opening to this cairn has collapsed, making it difficult to determine the existence of this chamber using intrusive methods. Through the use of muon tomography we are able to determine the position and size of the chamber.

Currently we are working with Monte Carlo simulations to gain knowledge on the data we can expect to see in the upcoming project. An animation of such a scan is shown below, with the chamber becoming visible after multiple days of data collection. The passage was left out in this simulation for simplification.

Awards & Funding:

• First Place at 2021 Physics Departmental Poster Competition ($100) (Webb)
• Third Place at 2021 Physics Departmental Poster Competition ($50) (Binu)
• First Place at 2020 Physics Department Poster Competition ($100) (Cano)
• Second Place at 2020 Physics Department Poster Competition ($100) (Shanto)
• TRUE Undergraduate Research (UR) Travel Funding Award ($1000) 2019 (Moosajee)
• TRUE Undergraduate Research (UR) Travel Funding Award ($1000) 2019 (Shanto)
• APS Student Travel Award ($1000) 2019 (Shanto)
• 2019 Gulf Coast Undergraduate Research Symposium Travel Fund (airfare ticket and hotel stay paid for) (Perez)
• TRUE Undergraduate Research Project Funding Award ($1000) (Perez)
• First Place at 2019 Physics Department Poster Competition ($100) (Shanto)
• Third Place at 2019 Physics Department Poster Competition ($100) (Perez)
• Outstanding Undergraduate Student Poster Presentation Award at Texas Section of APS Conference 2019 ($50) (Shanto)
• Honorable Mention for Undergraduate Student Poster Presentation at Far West Section of APS Conference 2019 (Shanto)

Publications

High-Resolution Muography Using a Prototype Portable Muon Telescope, Journal of Undergraduate Reports in Physics (Vol.30, Issue 1)

Presentations

• Poster Presentation at the 2022 TTU Undergraduate Research Conference (Binu)
• Oral Presentation at the 2022 TTU Undergraduate Research Conference (Bradley)
• Poster Presentation at the 2022 TTU Undergraduate Research Conference (Howard)
• Poster Presentation at the 2022 TTU Undergraduate Research Conference (Schneider)
• Oral Presentation at the 2022 TTU Undergraduate Research Conference (Chavez)
• Oral Presentation at Fall 2021 Meeting of the Texas Sections of APS (Binu)
• Oral Presentation at 2021 Gulf Coast Undergraduate Research Symposium (Bradley)
• Oral Presentation at 2021 Gulf Coast Undergraduate Research Symposium (Binu)
• Poster Presentation at 2021 TTU Physics Departmental Poster Competition (Binu)
• Poster Presentation at 2021 TTU Physics Departmental Poster Competition (Webb)
• Oral Presentation at 2021 Annual APS Conference (Shanto)
• Colloquium Presentation for Physics Department, Texas Tech University 2021 (Shanto & Cano)
• Poster Presentation at 2020 Physics Department Poster Competition (Shanto & Cano)
• Poster Presentation at the Annual Texas Section of APS Conference 2020, University of Texas Arlington (Shanto)
• Poster Presentation at the Annual Texas Section of APS Conference 2019, Texas Tech University (Shanto)
• Oral Presentation at the Annual Texas Section of APS Conference 2019, Texas Tech University (Perez)
• Poster Presentation at the International Conference for Physics Students 2019, University of Köln (Moosaje)
• Oral Presentation at the 2019 Gulf Coast Undergraduate Research Symposium, Rice University (Perez)
• Poster Presentation at the Annual Far West Section of APS Conference 2019, Stanford University (Shanto)
• Poster Presentation at 2019 Physics Department Poster Competition (Shanto & Perez)
• Poster Presentation at the 11th annual TTU Undergraduate Research Conference 2019 (Moreno)
• Oral Presentation at the Texas Tech University Annual Virtual Research Conference 2020 (Shanto)
• Poster Presentation at the Texas Tech University Annual Virtual Research Conference 2020 (Perez)

4. Radiation-Hard Fiber R&D

Some of the more common materials in high-energy and nuclear physics experiments are the scintillators for detection of charged particles. Although these ubiquitous materials are extremely useful and versatile, they suffer degradation when exposed to moderate levels of radiation. Much has been written about the possible damage mechanisms of organic and inorganic scintillators, but a truly radiation-hard scintillator remains elusive today. The need for radiation-hard scintillators beyond what is available today is the primary reason why we explore cerium-doped fused-silica (SiO2:Ce3+) fibers. The clear fused-silica fibers, because of their superior radiation-hardness, are good candidates to host inorganic (rare-earth) scintillating dyes. The choice of cerium as a starting point in this research program was based on its apparent high light yield, its peak emission wavelength that is appropriate for standard PMTs or SiPMs, and its potential radiation hardness. Other rare earths may also be appropriate as dyes. Praseodymium, for example, is faster, with an emission peak at shorter wavelength compared to cerium.

Our continued R&D program in radiation-hard fibers started in 2015 with a US Department of Energy grant. We produced several prototype scintillating cerium-doped fused-silica fibers (some pictured above) in collaboration with Polymicro Technologies in Phoenix, AZ, USA. Our collaborators include colleagues from ETH-Zurich, Milano-Bicocca, INFN-Milano, INFN- Torino, and University of Akdeniz (Antalya, Turkey).  We routinely use the irradiation facilities at Sandia, Los Alamos, University of Maryland, and ENEA in Rome.  

Our work in radiation-hard optical fibers for particle physics applications goes back over two decades. We led the R&D activities in clear fused-silica fibers for the CMS Forward Calorimeters in the late 1990s. These fibers were "new" then but they are still performing beautifully at the LHC and providing high quality data.  In 2004, Ray Thomas performed extensive tests on clear synthetic fused-silica fibers for his MS thesis.  Some of the more recent studies with cerium-doped fused-silica fibers are summarized in Esra Kendir's PhD thesis and the publications listed below.  We continue refining our fiber design and production in order to achieve truly radiation-hard fibers for a wide range of applications.

Publications

• N. Akchurin, N. Bartosik, J. Damgov, F. De Guio, G. Dissertori, E. Kendir, S. Kunori, T. Mengke, F. Nessi-Tedaldi, N. Pastrone, S. Pigazzini and S. Yaltkaya, Cerium-doped fused-silica fibers as wavelength shifters, Journal of Instrumentation, 14(06), June 2019, https://doi.org/10.1088/1748-0221/14/06/t06006
• N. Akchurin, E. Kendir, S. Yaltkaya, J. Damgov, F. De Guio and S. Kunori, Radiation-hardness studies with cerium-doped fused-silica fibers, Journal of Instrumentation, 14(03), March 2019, https://doi.org/10.1088/1748-0221/14/03/p03020
• N. Akchurin, C. Cowden, J. Damgov, C. Dragoiu, P. Dudero, J. Faulkner and S. Kunori, Cerium-doped scintillating fused-silica fibers, Journal of Instrumentation, 13(04), April 2018, https://doi.org/10.1088/1748-0221/13/04/p04010

Presentations

• T. Pelota, Radiation Hardness Study of HGCAL v1-Prototype Si Sensors, IPRD19, New York, NY, 9-12 April 2022
• F. De Guio, Cerium-Doped Fused-Silica Fibers for Particle Physics Detectors, IPRD19, Siena, Italy, 14-17 October 2019
• E. Kendir (poster), Radiation-hardness studies with cerium-doped fused-silica fibers, TTU Departmental poster competition third place, 23 October 2018
• E. Kendir (poster), Radiation-hardness studies with cerium-doped fused-silica fibers, Texas Section of American Physical Society Meeting, University of Houston, 19-20 October 2018
• N. Akchurin, Cerium-doped fused-silica fibers, TIPP2017, Beijing, China, 22 May 2017
• F. Nessi-Tedaldi, Energy resolution and timing performance studies of a W-CeF3 sampling calorimeter prototype with a wavelength-shifting fiber readout, TIPP2017, Beijing, China, 25 May 2017
• J. Damgov, Cerium-doped Scintillating fused-silica fibers, SCINT2015, Berkeley CA, USA, 7-12 June 2015

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5. CaloX- Extreme Calorimetry

How is the energy of particles that come out of collisions in colliders or in outer space measured? Calorimeters traditionally fulfill this function, and experimentalists have been making steady progress toward improved energy resolution and response in the last decade or two. A significant advance was brought about through TTU's dual-readout technique, by which two types of signals from scintillation and Cherenkov photons are recorded for the same shower. These two signals are in turn used to determine the electromagnetic fraction that tends to substantially fluctuate in hadronic showers. Measuring this fraction for each event helps improve the energy measurement as well as preserve response linearity. Different versions of this technique are now being considered for future experiments.

Another approach that has been proposed is "imaging calorimetry," which reconstructs the shower "image" by using signals from small active elements. Advances in sensor technology and image processing algorithms may lead to the creation of better tools for energy measurements, as well as insights into physics objects such as jets. Our group has decided to push the limits of this approach by simulating every particle interaction in a calorimeter and by analyzing the "images" that emerge from these showers. We call this project "extreme calorimetry," CaloX for short.

During Summer 2023 we tested new Silicon Photomultipliers at CERN to determine the possible spatial resolution in such a calorimeter. Currently, we are working on distinguishing pulses that arrive in near proximity to each other in the calorimeter. We are planning to rebuild the DREAM module with a new readout system to apply the new advancements in electronics and test the calorimeter at CERN during Summer 2024.

Publications

• The (Un)reasonable Effectiveness of Neural Networks in Cherenkov Calorimetry, Instruments 6 (2022) 4, 43
• Deep Learning Applications for Quality Control in Particle Detector Construction, arXiv:2203:08969
• Perspectives on the Calibration of CNN Energy Reconstruction in Highly Granular Calorimeters,arXiv:2108.10963
• On the Use of Neural Networks for Energy Reconstruction in High-granularity Calorimeters, 2021, JINST 16 P12036

Presentations

• US Perspective in Calorimetry R&D, Plenary talk given at the 20th International Conference on Calorimetry in Particle Physics (CALOR 2024), Tsukuba, Japan, May 2024 (N. Akchurin)
• Vertex Imaging Calorimetry using AI/ML Tools, Plenary talk given at the 20th International Conference on Calorimetry in Particle Physics (CALOR 2024), Tsukuba, Japan, May 2024 (S. Kunori)
• High-granularity Dual-readout Calorimeter: Evolution of a classic prototype, Plenary talk given at the 20th International Conference on Calorimetry in Particle Physics (CALOR 2024), Tsukuba, Japan, May 2024 (N. Akchurin)
• Precision Timing in Calorimeters, 2024 European Edition of International Workshop on the Circular Electron-Positron Collider (CEPC), Marseille, France, April 2024 (N. Akchurin)
• Exploiting Cherenkov in Calorimetry, DRD-on-Calorimetry Workshop, CERN, April 2024 (N. Akchurin)
• "Understanding Baryon Production in Calorimeters for High-Energy Physics: Insights from Monte Carlo Simulations", Gulf Coast Undergraduate Research Symposium, Rice University, 2023 (O. Schneider)
• "Precision Timing and their Application in Calorimetry", ECFA Detector R&D Roadmap Symposium – Calorimetry, 2021 (N. Akchurin)
• “Longitudinal Segmentation of Multi-readout Fiber Calorimeters by Timing for 3D Imaging Calorimetry”, CPAD Instrumentation Workshop, 2021 (Shuichi Kunori)