US-Japan Meeting 2023

Imin International Conference Center at East-West Center

Imin International Conference Center at East-West Center


Thank you for your interest in attending The 45th meeting of the US-Japan Science and Technology Cooperation Program in High Energy Physics. The event has concluded and the next meeting will be hosted in Japan, more details to come. 

Congratulations to the poster award recipients; 


"Studies of R(D) and R(D*) at Belle II using an inclusive tagging method"

by Boyang Zhang,
University of Hawaii, Manoa


"Advanced Material Studies for High Intensity Proton Production Targets and Windows”

by Sujit Bidhar,
Fermi National Accelerator Laboratory


"Development of AC-LGAD detectors with finer pitch electrodes suitable for future hadron collider experiments" 

by Sayuka Kita,
University of Tsukuba and KEK




If you have any questions pertaining to this past event please contact Stephany Tone,




Dr. Natalie Roe
    • 8:30 AM 9:00 AM
      Symposium Check In 30m Keoni Auditorium

      Keoni Auditorium


      Pick up attendee badges
      A separate work space is located in Kamehameha Conference room for attendee use throughout the event.

    • 9:00 AM 10:30 AM
      Plenary Talks 1h 30m Keoni Auditorium

      Keoni Auditorium


      Session Chair - Natalie Roe (LBNL)

    • 10:30 AM 11:00 AM
      Morning Refreshments 30m
    • 11:00 AM 12:00 PM
      Plenary Talks 1h Keoni Auditorium

      Keoni Auditorium


      Session Chair - Toru Iijima (Nagoya University)

    • 12:00 PM 2:00 PM
      Lunch 2h JCM Senior Committee Working Lunch Closed Session in Oahana Conference Individual Symposium Attendee Boxed Lunch pick up in Makana Conference

      JCM Senior Committee Working Lunch Closed Session in Oahana Conference Individual Symposium Attendee Boxed Lunch pick up in Makana Conference


      JCM Senior Committee Working Lunch Closed Session in Ohana Conference
      Individual Symposium Attendee Boxed Lunch pick up in Makana Conference

    • 2:00 PM 3:30 PM
      Plenary Talks 1h 30m

      Session Chair - Dmitri Denisov (BNL)

    • 3:30 PM 4:00 PM
      Afternoon Refreshments 30m
    • 4:00 PM 5:00 PM
      Poster Session 1h

      Posters are located in the Kaniela and Sarimanok adjacent conference spaces. Poster participants may access these rooms at 8am on Monday, May 22.

      • "Recent updates on superconducting magnet materials including TEM of irradiated REBCO, mechanical testing of insulating materials, and microstructural changes to irradiated low-temperature solders." 5m

        Modern superconducting magnets are used for a variety of applications at the forefront of research. For example, High-Energy Physics relies on high-fidelity Nb3Sn and future Fusion possibly on REBCO. For the US-Japan collaboration we look at the radiation effects on these conductors and the insulation materials they critically rely on. In one study, industry-standard CTD-101K epoxy resin system was examined against ‘mix-61’ developed by the National High Magnetic Field Laboratory (NHMFL) and the resin system developed for the ATLAS Experiment’s End Cap Toroid (ECT) magnet. Physical analysis, mechanical testing, and microscopy revealed generally superior properties for CTD-101K, though pristine mix-61 and ECT exhibited greater strength and toughness at 77 Kelvin. Upon irradiation however, NHMFL mix-61 and ATLAS-ECT saw precipitous declines in performance with 101K showcasing unparalleled radiation resistance. In another study we simulate transmutation effects and use Helium-Implantation Microscopy to emulate (n,α) effects and study radiation swelling. Finally, we undertook a study to use machine learning on Transmission Electron Microscopy images to quantify how the radiation affects the microstructure.

        Speaker: Christopher Reis (LBNL)
      • "CP asymmetry measurement in charm Baryon decay as part of Ozaki Fellowship at Belle II " 5m

        I got the opportunity to do my research via the Ozaki fellowship during summer at KEK, Japan where the Belle II experiment is located. In this talk I will summarize physics analysis project progress and results. In physics analysis I looked at measurement of CP asymmetry parameter in single cabibbo suppressed charm baryon decay: Ξ+c → Σ+π+π−, which is relatively unexplored field and can also be potential source for New Physics to explain matter-antimatter asymmetry we see in Universe.

        Speaker: Anil Panta
      • "Laser-plasma accelerators research for high energy physics at the BELLA Center" 5m

        This presentation summarizes the current activities of the BELLA Center on laser-plasma accelerator (LPA) research for high energy physics. The Center has been developing the physics and technology of advanced laser-driven and plasma-based ultra-high gradient accelerators. At the flagship 1-Hz 1-PW laser facility, the development of 10-GeV class LPA modules in series is envisioned as the path to a high energy collider at TeV energies and beyond. To achieve the desired luminosities required for such a collider, high repetition-rate (tens of kHz) laser sources are needed. To meet these requirements, the BELLA Center is pursuing a promising technology based on the coherent combining of fiber lasers. This work is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Contract No. DE-AC02-05CH11231.

        Speaker: Kei Nakamura
      • "Research of Copper Thermal Spray Coating for Mitigating Electron Cloud Effect" 5m

        The electron cloud effect (ECE) has posed serious challenges in recent high-intensity proton and positron rings. One of the applicable solutions is preparing a surface with a low secondary electron yield (SEY) on the inner wall of beam pipes. In this study, we used a commercial method called “thermal spray”, where copper powder was melted and sprayed onto an aluminum substrate to create a rough surface, and was investigated for the first time as a method for producing a low SEY surface. After an electron exposure of ≈ 1 ×10-1 C/mm2 at an energy of 350 eV, the lowest δmax (the maximum SEY within scanning) of the copper thermal spray (T.S.) coating reached ~0.7.
        The Emax (the incident electron energy corresponding to δmax) of T.S. coating was found to be inversely related to the surface temperature during spraying. The roughness parameters and surface composition were measured to clarify the key factors affecting SEY. In addition, to check the applicability of T.S. coating in accelerators, its outgassing rate, adhesive strength, impedance and dust generation rate were measured as a reference.
        Finally, an aluminum beam pipe with a T.S. coating was produced and installed in the positron ring of SuperKEKB to measure the electron density around the beam. The measured electron densities were compared with those obtained from other beam pipes with different inner surfaces, and also investigated using a simulation code.
        The results show that the outgassing rate and adhesive strength of T.S. coating were acceptable. However, the amount of dust and impedance were not inconsiderable. The measured electron densities of the T.S.-coated beam pipe was comparable with that of the TiN-coated beam pipe even under the influence of the uncoated aluminum screen. Therefore, the T.S. coating can be considered as a candidate technology for reducing ECE, while there are still room for improvement. This study can provide a new and useful information for researchers in this field in developing a low-SEY coating on beam pipes.

        Speaker: Mulee Yao
      • "First survey of centimeter-scale AC-LGAD strip sensors with a 120 GeV proton beam" 5m

        We will present the first beam test results with centimeter-scale AC-LGAD strip sensors, using the Fermilab Test Beam Facility, and a study of the performance of AC-LGAD sensors as a function of their thickness. Sensors of this type are envisioned for applications that require large-area precision 4D tracking coverage with economical channel counts, including timing layers for the Electron Ion Collider (EIC), and space-based particle experiments. Long strip sensors with sparse readout offer better cost and performance for applications where channel count or electrical power density is a constraint. Thanks to the excellent signal to noise ratio in AC-LGADs, sparse readout can be exploited without significant degradation of spatial or time resolution, which is demonstrated in our studies. A survey of sensor designs is presented, with the aim of optimizing the electrode geometry for spatial resolution and timing performance. We will present our studies of the sensor geometry optimization to maintain the desirable sensor performance characteristics with increasingly larger electrodes.

        Speaker: Christopher Madrid
      • "Development of AC-LGAD detectors with finer pitch electrodes suitable for future hadron collider experiments" 5m

        The Low-Gain Avalanche Diode (LGAD) technology is for a semiconductor detector to improve the timing resolution. We are developing AC-LGAD detectors suitable for particle tracking in future hadron colliders, aiming to realize both high timing (~30ps) and spatial (~o(10)um) resolutions. To achieve such spatial resolution in very high particle density environments, we investigate to make the electrode pitch finer. We have succeeded in observing AC-LGAD signals of pixels with pitch down to 50 um while keeping timing resolution uniform over the active area. We present recent performance results of the AC-LGAD detectors fabricated by HPK including the basic detector characteristics, understanding of timing resolution, and improvement of radiation tolerance.

        Speaker: Sakuya Kita
      • "High efficient H- beam stripping by multi-pulse train High Efficient H-beam stripping by multi-pulse train laser with multi-reflection imaging optics" 5m

        In Japan High Intensity Proton Beam Facility(J-PARC), high current and high energy
        proton beam are generated with the combination of LINAC and Synchrotron accelerators. Inside this accelerator, H- ion beams from the LINAC are charge exchanged to proton beam with charge stripping carbon foil. However, recent power-up advanced improvement in J-PARC, the life time of this foils are shorter and recycling process affects the operation of high current ion beam.
        To solve this problem, we have proposed material free method with high power lasers. In this scheme, we have three steps of electron stripping process from H- ions to H+ protons. For the first step, one electron of H- ions is ionized with 1micron laser pulse. In this case, the electrons are relatively weakly bonded and bound-free transition process is enough to use. The estimated pulse energy and pulse duration at the interaction area is 7 mJ and 100ps, respectively for 99% conversion efficiency. To consider high repetition rate (354MHz) of micro pulse in J-PARC facility and macro pulse(0.5ms) of the pulse train with 25Hz macro pulse repetitive rate, this energy and total power is 28.4kW level. It is not infeasible level in recent laser technology, but to consider the indeed small cross section of light-ion interaction, we need to recycle the laser energy with multi reflection optics. As a result, coupled with multi-reflection overlapping system, we achieve 25% conversion efficiency from H- beam to H0 beam with this PoP laser system. Each step is 20 ps and 260ps pulse waveform is measured for the first time in the light-beam interaction method. We are now developing main laser system to install at the main J-PARC LINAC accelerator area.

        Speaker: Yurina Michine
      • "Neutrino Interaction Measurements for Supernova Detection at the Spallation Neutron Source" 5m

        The intense pulsed neutrinos at the Spallation Neutron Source (SNS) present a unique opportunity to measure low-energy neutrino interactions on 16-O including inelastic charged-current and neutral-current interactions in the few tens of MeV range. While these interactions have never been measured at this energy, they are of great importance for supernova detection in Super-Kamiokande and Hyper-Kamiokande, for which signals will be highly complementary to those of DUNE. The COHERENT collaboration is deploying a heavy water detector optimized for a neutrino flux
        normalization using the charge current interactions on the deuteron. While the instrument will have some sensitivity for such a cross section measurement on oxygen, a precision measurement could be made with a larger, more optimally instrumented detector at the upgraded SNS First Target Station or at the future Second Target Station that would further enable the disentangling of the subdominant electron neutrino and neutral current components from the inverse beta decay interactions in the large water-based experiments.

        Speaker: Jason Newby
      • "Advanced Material Studies for High Intensity Proton Production Targets and Windows" 5m

        With increasing beam intensities of future multi-megawatt accelerator facilities, various beam intercepting components such as beam windows, targets etc., will undergo greater thermal stress waves and ensuing dynamic loads during operation as well as various radiation damage that will limit its service life. Hence there is a need to understand these damage mechanisms in accelerator condition and mitigate these issues. Here we present recent advances in material testing, proton beam irradiation induced damage characterization and its effect on mechanical properties on existing materials and new materials. Thermal-shock experiment was carried out using intense pulsed proton beam at CERN on variety of novel materials and alloy to check the survivability of potential novel materials in future high-power accelerators. Tensile, fatigue tests were carried out on proton irradiated Ti-alloys which shows the effect of radiation damage on mechanical properties and fatigue life. Molecular dynamics simulations are carried out to better understand radiation damage in various Ti-alloys. A bend fatigue tester is modified to have a grip mechanism to hold miniature irradiated samples and a new design for bend fatigue tester is presented. Apart from this, DPA cross section measurements were successfully carried out with 120GeV proton beam to validate the simulation results in excess of 30GeV energy regime.

        Speaker: Sujit Bidhar
      • "Developments in Toughened Fine-Grained Recrystallized Tungsten for High Intensity Proton Production Targets" 5m

        In high-energy proton accelerator facilities, protons accelerated to several hundred MeV to several hundred GeV are irradiated to target materials, and the produced secondary particles are used in experiments to elucidate particle physics, and materials and life sciences. The recent major accelerator facilities have been limited in beam power not by their accelerators, but by target survivability. When secondary particles are transported to the experimental area, the spatial spread of the secondary particle source can be suppressed by increasing the density of the target material, thereby improving the transport efficiency. Therefore, tungsten, hereafter W, is expected to be used as a target material all over the world. However, W is known to exhibit recrystallization embrittlement and irradiation embrittlement. High Energy Accelerator Research Organization has established an industry-academia, an international, and a domestic collaboration to develop Toughened, Fine Grained, Recrystallized, TFGR W, to surmount the shortcomings of the conventional W materials. TFGR W exhibits grain boundary reinforced nanostructures containing a high density of effective sinks for irradiation induced point defects, a Ductile-to-Brittle Transition Temperature down to around RT and enhanced resistances against damages by thermal shock/fatigue in the recrystallized state. In this presentation, recent progress in the development of TFGR-W will be presented. This program is supported by KEK-MTC collaboration, METI Monozukuri R&D Support Grant Program JPJ005698, JSPS KAKENHI Grant Number JP19H01913, JP21H04868, NIFS Collaboration Research program NIFS17KEMF101, U.S.-Japan Science and Technology Cooperation Program in High Energy Physics “Advanced Material Studies for High Intensity Proton Production Targets and Windows”, RaDIATE (Radiation Damage In Accelerator Target Environments) international collaboration.

        Speaker: Shunsuke Makimura
      • "Studies of R(D) and R(D*) at Belle II using an inclusive tagging method" 5m

        B meson semileptonic decays involving b->c transitions provide rich information on the Standard Model (SM) and physics beyond it. The ratios of branching fractions R(D) and R(D) are sensitive probes for testing lepton flavor universality in the SM, and the q^2 distribution has great potential to reveal new physics. Although limited by statistical uncertainty, the world average of R(D) and R(D) to date is 3-sigma from the SM. More statistics can be achieved with more data or a new analysis method that does not require high purity. This poster presents a MC sensitivity study of new method based on inclusive tagging, which has about 10 times higher reconstruction efficiency than in previous measurements. We plan to use the Belle II LS1 dataset, which corresponds to 364/fb.

        Speaker: Boyang Zhang
      • "Dark photon and dark Z mediated B meson decays" 5m

        We study flavor changing neutral current decays of B and K mesons in the dark U(1)_D model, with the dark photon/dark Z mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of B → K^(∗) l^+ l^−, with l = μ, e, and B_s → φμ^+μ^−, the allowed parameter space is ruled out by measurements of atomic parity violation, K^+ →μ^+ + invisible decay, and B_s – \bar{B}_s mixing, among others. To evade constraints from low energy data, we extend the model to allow for (1) additional invisible Z_D decay, (2) a direct vector coupling of Z_D to muons, and (3) a direct coupling of Z_D to both muons and electrons, with the electron coupling fine-tuned to cancel the Z_D coupling to electrons via mixing. We find that only the latter case survives all constraints.

        Speaker: Ahmed Rashed
      • "Enabling the Next-Generation Waveform Readout for the K-long and Muon Detector at Belle II" 5m

        The Belle K-long and muon (KLM) sub-system was upgraded for Belle II to replace a large portion of the resistive plate counters with 18,560 scintillator channels. The scintillators are made from polyvinyl toluene, embedded with a central wavelength shifting fiber, and instrumented with Hamamatsu silicon photomultipliers (SiPMs). SiPM hits are read out using the TARGETX waveform-sampling and triggering ASIC. These TARGETX ASICs have been operating in a triggering-only mode since the beginning of the Belle II experiment. This work describes the efforts and progress toward utilizing the waveform-sampling feature of these ASICs. To this end, firmware has been prepared which both controls and reads out data from 10 TARGETX ASICs. This so-called waveform readout firmware is responsible for sending slow-control to the ASICs, aligning the analog sampling array with detector c-time, logging primitive triggers from TARGETX channels and later comparing those trigger timestamps with global trigger c-time to determine whether hits were present, masking analog storage array addresses during digitization, initiating digitization on those addresses, providing time-sensitive signals to shift out data from the TARGETX ASICs, measuring pedestal values for every storage element in the TARGETX analog storage array, interfacing with an external static RAM for writing and reading of those pedestal values, performing on-the-fly pedestal subtraction on waveform data, extracting leading-edge time and peak voltage from the SiPM hits, and filling a firmware-based histogram with peak voltages for the purpose of offline SiPM gain calibration. Currently, the waveform firmware development is complete, and integration & deployment of the firmware on the Belle II KLM detector is underway.

        Speaker: Christopher Ketter
    • 5:15 PM 5:30 PM
      Group Transportation to JCC

      There will be 2 shuttles providing transportation to the Japanese Cultural Center for the Nalu/CAEN sponsored reception. Please see below;

      Shuttle 1: 50 person bus departing EWC at 5:30pm, returns to EWC , departing JCC at 8:40pm

      Shuttle 2: 25 person bus departing EWC at 5:30pm, returns to Kaimana Beach Hotel departing JCC at 8:40pm

    • 5:45 PM 8:30 PM
      Welcome Reception 2h 45m Japanese Cultural Center of Hawaii

      Japanese Cultural Center of Hawaii

      2454 So. Beretania St, 5th Flr Honolulu, Hawaii 96826

      This reception is sponsored by Nalu Scientific and CAEN

      • Bar opens at 5:45pm - 2 complimentary drink tickets per attendee and a cash bar is available thereafter.
      • Buffet line opens at 6:15pm
      • Reception ends at 8:30pm

      For those who choose to drive independently, parking is available at JCC for $8

    • 9:00 AM 10:20 AM
      Plenary Talks - Research Progress Reports 1h 20m

      Session Chair - Yasuhiro Okada (KEK)

    • 10:20 AM 10:50 AM
      Morning Refreshments 30m
    • 10:50 AM 12:30 PM
      Plenary Talks - Research Progress Reports 1h 40m

      Session Chair - Bonnie Fleming (FNAL)

    • 12:30 PM 2:00 PM
      Lunch 1h 30m JCM Senior Committee Working Lunch Closed Session in Ohana Conference Individual Symposium Attendee Lunch in Wailana Conference

      JCM Senior Committee Working Lunch Closed Session in Ohana Conference Individual Symposium Attendee Lunch in Wailana Conference

    • 2:00 PM 3:10 PM
      Plenary Talks - Research Progress Reports 1h 10m

      Session Chair - Naohito Saito (KEK)

    • 3:10 PM 3:40 PM
      Afternoon Refreshments 30m
    • 3:40 PM 4:25 PM
      Poster Competition Awards, Closing Remarks 45m

      Poster Awards (Dr. Natalie Roe)
      Closing Remarks (Dr. Yasuhiro Okada and Dr. Regina Rameika)

    • 4:25 PM 5:00 PM
      Signing Ceremony: US and Japan Signing and Group Photo Keoni Auditorium

      Keoni Auditorium