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Jung Research Group Part of the High Energy Physics Group

High Energy Physics


The Jung group focuses on research related to the analysis of vast data sample using cutting-edge analysis techniques and Instrumentation R&D to develop future detector for high energy physics. We are also engaged in quantum algorithm development at the intersection of quantum physics and advanced data analysis techniques, including machine learning on quantum computers for high energy physics and business applications. We offer UG research opportunities in all areas at all times, just get in contact with the Jung group.

Data Analysis

The focus of our research is to shed light on the question of what stabilizes the electroweak scale or more precisely the Higgs mass. A future more complete theory would allow to calculate the Higgs mass and in our current best understanding (known as standard model of particle physics) the Higgs mass would receive quantum loop corrections. The loops are in fact dominated by top quarks since these are the most heavy known elementary particles.

Figure 1: Loop corrections to the Higgs mass
are dominated by top quark loops.

The loop corrections shift the Higgs mass effectively to the enormous Planck scale. However, the experimentally observed Higgs boson has a mass of about 125 GeV, much lower than the Planck mass either potentially indicating beyond the standard model effects to cancel these corrections or an incredible fine-tuning in that future theory.

We search for beyond the standard model effects by employing the top quark sector which is closely tied to the Higgs boson sector. An elegant way of avoiding the loop corrections in a future theory is by the exact cancellation of these loop corrections due to a partner of the top quark. Members of the group carried out direct searches for vector-like top quark partners up to highest achievable mass scales (see a Preliminary result here: CMS-B2G-16-002). In the absence of clear indications in the early 13 TeV data the Jung group has shifted the research focus more and more to search indirectly for any signs of deviations from the standard model via precision measurements in the top quark sector.


Figure 2: The unfolded distribution of the azimuthal
opening angle between two leptons in top quark events.

An example being the analysis of top quark spin correlations via a multi-differential cross section measurement, which allows to pinpoint any non-SM contributions provided the systematic uncertainties are well understood and under control. An example being the distribution of the opening angle of the decay leptons steming from the decay of the top quarks, refered to as |Δφ(ll)| in Figure 2. This and other highly precise differential distributions measured by CMS are sensitive to the spin correlation and polarization: PRD 100 (2019) 072002. Results are used to challenge the modeling of how top quarks are produced as predicted by the Standard Model theory.

Please take a look at the Open Positions/Contact page for Ph.D. and undergraduate research opportunities related to CMS data analysis in the group. Undergraduate researchers are an integral and critical part of the research effort.

The high-luminosity upgrade of the CMS detector

The LHC complex will undergo a series of upgrades (High Luminosity Phase of the LHC, HL-LHC) in order to increase the instantenous luminosity to unprecedented values at hadron colliders. The HL-LHC is expected to be ready for data taking in the 2020s with significant detector R&D already taking place now. The focus of the Jung group is on the instrumentation of the innermost region of the CMS tracking devices using silicon detectors. The Purdue Silicon Detector Lab is a state-of-the-art in-house facility for broad R&D aspects and assembly of silicon detectors for the HL-LHC.

Figure 1: Custom made sheets of individual
layers of 60 micron thick carbon fiber plys
employed as baseplates of the support
structures of silicon detectors.

The precise track information is the basis for the identification of particle jets originating from b-quarks, which is one of the most efficient methods to enhance H→bb decays, top quark decays and a large amount of beyond the standard model signatures. A silicon detector provides the precise track reconstruction required to perform this identification. Non-active materials (support, cooling, electronics) in a silicon detector degrade the performance of the track reconstruction of charged particles going through the silicon detectors. Hence, the R&D focus is on light-weight materials and their use for support structures of silicon detectors. In particular carbon fiber is at the center of the ongoing R&D activities, since it is light-weight and mechanically very strong.
Other examples being custom made carbon fiber sheets using an in-house facility, see Figure 1. These sheets are used to build mock-up silicon detector modules which are as close as possible to the real detector modules also using raw silicon. The mock-ups are employed to study and test the thermal performance under real conditions. The collected data is analyzed and compared to resuls of a finite element analysis of the expected heat distribution.  Figure 2 shows an example of a mock-up already equipped with temperature sensors. Jung’s group is doing R&D for future detectors, namely support structures for large future circular collider (FCC-ee, FCC-hh), muon collider and other future machines. The Jung group has submitted a white paper on future detector mechanics to the snowmass process and it is included in the WG report on solid state detectors.

Figure 2: Preparing a silicon detector mock-up
for thermal measurements using parts and
pieces of real silicon detectors.

Jung is an affiliated member of the Purdue Composite Manufacturing and Simulation Center and utilizes the facility to develop a variety of carbon fiber based superstructures supporting the entire inner silicon pixel detector. The total length of the cylindric superstructures is about 5.4m, composed of 4 half-cylinders each with about 2.7m length and additional larger tubes ranging in size between 0.5 to more than 2m. A first prototype of a shorter section ("step section") of the half-cylinders has been manufactured in February 2018 at the CMSC employing a 3D printed mold used to cure a layup of Carbon Fiber prepreg. Figure 3 shows the 3D printing process of the mold, which is then later used for the layup of the Carbon Fiber layup (top small insert), and the bottom insert shows a laser scan of the "step section" prototype. 


Figure 3: 3D printed mold and final cured
Carbon Fiber layup for a section of the large
supporting superstructure of the new CMS
phase II silicon pixel detector.


Most recently, Purdue researchers in the Purdue Silicon Detector Lab (PSDL) and the Composite Manufacturing & Simulation Center (CMSC) have worked together on the challenge of removing 35kW of heat relying on lightweight composite tracker support structures.  They have been creating prototype cylinders made of carbon fiber composites and have now officially created a working prototype that will be installed and tested at CERN near the end of 2022. Purdue CMS scientists currently work on more testing, metrology, loading scenarios, and once completed prepare the eventual shipment to CERN for more tests. Once the BTST prototype arrives at CERN and has been tested, the Purdue CMS team will work on design and manufacturing of the final full-length, 5.3m (16.4ft), structure between 2022-2023.  This build will rely on an external fabrication partner given the enormous size of the structure. Figure 4 shows the first prototype with full diameter but shorter length of about 1m, which was received in November 2021.

Figure 4: The large BTST prototype, measuring roughly eight feet across, barely fit through the doors of the lab at CMSC.

The Jung group is commissioning a cooling test stand employing liquid CO2 as coolant at the Purdue Silicon Detector Lab to facilitate local thermal tests of the mock-up modules build in house. Please take a look at the Open Positions/Contact page for Ph.D. and undergraduate research opportunities related to Detector R&D in the group. Undergraduate researchers are an integral and critical part of the research effort.

Detector R&D

The Jung group is engaged in Detector R&D for future detectors in high energy physics, e.g. Muon Collider, Elektron-Positron Collider or a Future Circular Collider (ee/hh/ep). Undergraduate researchers are an integral and critical part of the research effort.

We are very happy to have been awarded by DOE for R&D on the development of Detector mechanics of future tracking and calorimeter devices.

  • Low-mass support structures with integrated services for silicon detector systems - The Jung group joins forces with CMSC's Eduardo Vaca to utilize transformational techniques and approaches to design and manufacturing low-mass support structures with integrated services. We study solutions towards integrated cooling channels and light-weight mechanical support structures that are optimized for thermal performance and low radiation length.

    To understand the bottlenecks in material choices, we have studied the thermal performance of a hypothetical support structure inspired by the CMS Inner Tracker dee support structures. A schematic (half) multi-layer ``stack" of materials is sketched in Figure 5, with the cooling pipe at the bottom and the silicon device at the top. Figure 6 shows the temperature difference of the silicon chip with respect to coolant temperature as a function of the thermal conductivity of the various material layers. The shaded bands for the TIM layer and epoxy layer around the cooling pipe are determined by varying the nominal thickness of these layers by given amounts.

    Figure 5: Schematic view of the cross-section of a representative multi-layer support structure inspired by the CMS Inner Tracker dee structure.

    Figure 6: The temperature difference between the hottest point on the chip and the coolant as a function of the thermal conductivities of different layers of a hypothetical support structure shown in Figure 5. More details in the text.
  • CalVision project, titled “Maximum Information Calorimetry", where we are working towards the development of a basic thin walled small-square honeycomb structure resembling a future calorimeter cell. Such a structure utlizes light-weight composite support structure materials and should be able to support a realistic calorimeter.

Quantum Algorithm Development

The Purdue Quantum Science & Engineering Institute (PQSEI) provides a stimulating environment to foster the development and ideas of practical and impactful aspects of quantum science. The Jung group is engaged in research and development of quantum algorithms that solve computational challenges arising in times of the High-Luminosity LHC phase. We currently work with a quantum annealing system and are engaging in employing an IBM gate-based quantum computer as well.
The Jung group is part of an interdisciplinary team to solve real-world problems such as optimization, data science, business, finance, and economics by employing quantum computing resources. These resources are either quantum annealing system (DWave) or very recently also the IBM gate-based systems. An overview that also provides open positions for this effort can be found here: Quantum Informatics. We are members of the Midwest Quantum Collaboratory in the research area of Quantum Algorithms, Quantum machine learning, Data Analytics, and also Quantum sensor development.

Undergraduate Research

The Jung group regularly offers UG research projects mostly in Detector R&D topics but also in data analysis, please contact Prof Jung for details on how to sign on for such UG research projects. During summer break the Jung group regularly hosts UG students from the SROP, UREP-C, SURF, REU, and other programs. In summer 2018 Prof Jung offered a Study Abroad course for Purdue UG students to carry out a 2.5 months research project at the TU Dortmund, Germany. Furthermore, since summer 2018 the Jung group offers the exciting opportunity for UG students from the TU Dortmund, Germany, to carry out a 3-month research project - please check the News for a brief report of the first participants of the exchange program.

Research for undergraduate students

Undergraduate students at Purdue University can contact Prof Jung at any time and check for UG research projects in the Jung group. During summer breaks the Summer Stay Scholar program, see below, is open for applications by Purdue UG students as well. Other UG research opportunities are mentioned below.

  • Students from Universities in the Americas please check the SROP, SURF, UREP-C, REU programs for UG research projects in the Jung group.

  • UG students from Purdue University interested in going abroad - please check the Study Abroad program at Purdue University for a UG research project at the TU Dortmund, Germany. Typically, the official web page becomes available once the coming summer program is setup, typically by the end of September. A shortened version is provided below:

    • Prof Jung regularly offers a summer break study abroad program, intended for students pursuing a physics major (future iterations of this course could target students in the sciences in general). Its objective is to help students understand how basic science advances, and to introduce them to the large scientific collaborations (> 1000 scientists) of modern particle physics experiments. These large collaborations are multi-national entities and a variety of differences between a “research-culture” in any given country exists.

    • This course introduces students to basic research in a foreign country, namely Germany. Purdue study abroad candidates, who are accepted for the “Culture of research in Germany” study abroad course will be integrated into a high energy physics research group at the TU Dortmund. The local group members will supervise participants in daily research and non-research activities. It is expected that the Purdue Study Abroad participants will host the visitors of a similar “Study Abroad” program for students from the TU Dortmund at Purdue in the following year.

    • The study abroad programs destination is the TU Dortmund in the city of Dortmund, which is part of the former heavy industry “Ruhrpott” area in western Germany. Dortmund was founded around the year 882 and by now has about 600,000 inhabitants making it the 8th largest city in Germany. Dortmund represents the eastern boundary of the “Ruhr” area, a metropolitan city-like area, that is densily populated with about 8 million people. Many locals strongly support Borussia Dortmund, which is one of the most famous soccer clubs in Germany/Europe playing in Germany’s largest soccer stadium (capacity of 81,000).

    • The focus of the UG research projects at TU Dortmund (and within my group at Purdue) targets a similar goal: Development of novel particle detectors and data analysis for particle physics experiments. Hence, participants are integrated into research groups actively exchanging ideas and progress. Study abroad participants are expected to attend at least 4 group meetings of the Jung research group in the preceding spring semester.

    • A visit to CERN and the CMS experiment is usually done as part of the Study Abroad program.

  • UG students from Germany interested in a research project at Purdue University - please check the german TU Dortmund - PeP et al. Study Abroad program and DAAD program for UG research projects in the Jung group.

  • The Summer Stay Scholars is an on-campus summer scholarship for undergraduate students at Purdue University campuses that combines on-campus summer coursework with a research or internship experience in West Lafayette. If you are selected for Summer Stay Scholars, you will receive a $2,500 scholarship to go towards of your tuition and fees during the summer. A $2,500 scholarship would cover full tuition and fees for a resident student and be a sizeable decrease in the total cost for non-resident or international students. You'll not only receive the financial assistance, but the research or internship experience will greatly enhance your coursework as well as give you a head start on your career.

    My group regularly offers those opportunities for excellent Purdue Summer Stay scholars. The following link gives all relevant information including the scholarship application, which typically opens in mid January and has a deadline of end of February; as well as how to qualify for the scholarship: Purdue Summer Stay Scholar program