Equivariant transformer is all you need

Tomiya, Akio*; Nagai, Yuki

Proceedings of Science (Internet), 453, p.001_1 - 001_7, 2024/11

https://doi.org/10.22323/1.453.0001

Machine learning, deep learning, has been accelerating computational physics, which has been used to simulate systems on a lattice. Equivariance is essential to simulate a physical system because it imposes a strong induction bias for the probability distribution described by a machine learning model. However, imposing symmetry on the model sometimes occur a poor acceptance rate in self-learning Monte-Carlo (SLMC). On the other hand, Attention used in Transformers like GPT realizes a large model capacity. We introduce symmetry equivariant attention to SLMC. To evaluate our architecture, we apply it to our proposed new architecture on a spin-fermion model on a two-dimensional lattice. We find that it overcomes poor acceptance rates for linear models and observe the scaling law of the acceptance rate in machine learning.

Impact of using JENDL-5 on neutronics analysis of transmutation systems

Sugawara, Takanori; Kunieda, Satoshi

Proceedings of International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023) (Internet), 7 Pages, 2023/08

This study investigates the impact of the change from JENDL-4 to JENDL-5 on neutronics analysis of transmutation systems. As the transmutation systems, the following two systems are targeted: JAEA-ADS, a lead-bismuth cooled accelerator-driven system, and MARDS, a molten salt chloride accelerator-driven system. For the JAEA-ADS, the k-eff value increased 189 pcm from JENDL-4 to JENDL-5. It was found that the revisions of various nuclides affected to this difference. For example, the revision of N indicated an increase of 200 pcm from the JENDL-4 result. For the MARDS, it was found that the major revision of Cl and Cl cross sections was the main cause of the k-eff differences. This study confirmed that the difference in the nuclear data libraries still indicated differences in calculation results for the transmutation systems.

Optimizing fissile nuclide content analysis for delayed gamma-ray spectroscopy nuclear safeguards

Rodriguez, D.; Koizumi, Mitsuo; Rossi, F.; Takahashi, Tone

Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 3 Pages, 2022/12

Evaluation of detector performances of new thin position-sensitive scintillation detectors for SENJU diffractometer

Nakamura, Tatsuya; To, Kentaro; Koizumi, Tomokatsu; Kiyanagi, Ryoji; Ohara, Takashi; Ebine, Masumi; Sakasai, Kaoru

Proceedings of 2022 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room Temperature Semiconductor Detector Conference (2022 IEEE NSS MIC RTSD) (Internet), 2 Pages, 2022/11

https://doi.org/10.1109/NSS/MIC44845.2022.10399279

A new thin position-sensitive scintillation neutron detectors have been developed to replace present scintillation detectors in SENJU diffractometer at J-PARC MLF. The SENJU diffractometer originally composed of 37 position-sensitive detectors, where each detector has neutron sensitive area of 256 256 mm with a pixel size of 4 4 mm. To renew some original detectors the new detectors have been developed based on ZnS scintillator and wavelength-shifting fibers technology. The developed replacement detectors were designed with a thin thickness of 12 cm, which is 40% of the original detector. The new detectors have also improved detector performances to the original ones in terms of detection efficiency (60% for 2-A neutrons) and count uniformity (5-8%). The produced six detector modules have been implemented to the beamline after checking their detector performances in the lab.

Axial U(1) symmetry at high temperatures in lattice QCD with chiral fermions

Aoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kanamori, Issaku*; Kaneko, Takashi*; Nakamura, Yoshifumi*; Rohrhofer, C.*; Suzuki, Kei

Proceedings of Science (Internet), 396, p.332_1 - 332_7, 2022/07

https://doi.org/10.22323/1.396.0332

The axial U(1) anomaly in high-temperature QCD plays an important role to understand the phase diagram of QCD. The previous works by JLQCD Collaboration studied high-temperature QCD using 2-flavor dynamical chiral fermions such as the domain-wall fermion and reweighted overlap fermion. We extend our simulations to QCD with 2+1-flavor dynamical quarks, where the masses of the up, down, and strange quarks are near the physical point, and the temperatures are close to or higher than the pseudocritical temperature. In this talk, we will present the results for the Dirac spectrum, topological susceptibility, axial U(1) susceptibility, and hadronic collelators.

The Phi meson in nuclear matter in a transport approach

Gubler, P.

Proceedings of Science (Internet), 380, p.215_1 - 215_5, 2022/05

https://doi.org/10.22323/1.380.0215

Based on my recent research, I will explain about my numerical simulation of pA reactions (p: proton, A: nucleus), which are used to study the meson in nuclear matter. I will particularly focus on the question of how the modification of the meson spectral function in nuclear matter influences the experimentally observed di-lepton spectrum.

The Energy spectrum of forward photons measured by the RHICf experiment in = 510 GeV proton-proton collisions

Sato, Kenta*; Tanida, Kiyoshi; 19 of others*

Proceedings of Science (Internet), 358, p.413_1 - 413_8, 2021/07

https://doi.org/10.22323/1.358.0413

Axial U(1) symmetry and mesonic correlators at high temperature in lattice QCD

Suzuki, Kei; Aoki, Shinya*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*

Proceedings of Science (Internet), 363, p.178_1 - 178_7, 2020/08

https://doi.org/10.22323/1.363.0178

We investigate the high-temperature phase of QCD using lattice QCD simulations with dynamical Mbius domain-wall fermions. On generated configurations, we study the axial symmetry, overlap-Dirac spectra, screening masses from mesonic correlators, and topological susceptibility. We find that some of the observables are quite sensitive to lattice artifacts due to a small violation of the chiral symmetry. For those observables, we reweight the Mbius domain-wall fermion determinant by that of the overlap fermion. We also check the volume dependence of observables. Our data near the chiral limit indicates a strong suppression of the axial anomaly at temperatures 220 MeV.

Development of the neutron polarizer for the T-violation search using compound nuclei

Okudaira, Takuya; Oku, Takayuki; Sakai, Kenji; Ino, Takashi*; Hayashida, Hirotoshi*; Hiroi, Kosuke; Shinohara, Takenao; Kakurai, Kazuhisa*; Aizawa, Kazuya; Shimizu, Hirohiko*; et al.

Proceedings of Science (Internet), 356, p.029_1 - 029_5, 2019/12

https://doi.org/10.22323/1.356.0029

The technology development section carries out the development of the neutron polarization device: He Spin Filter. It is often used for the fundamental physics region. In order to explain the matter-dominated universe, a time reversal violation is necessary and searches for new physics are conducted in the world. The T-violation search using a polarized neutron beam is planned at J-PARC. A large He spin filter is needed to polarize high energy neutrons for the experiment and is developed in JAEA. Recently, we developed the accurate measurement system to evaluate the polarization of He and a vacuum system to make the He spin filter, and large He spin filters for epi-thermal neutron was made using the system. The current status of the development of the He spin filter will be talked.

A Submillimeter spatial resolution scintillation detector for time-of-flight neutron diffraction imaging

Nakamura, Tatsuya; Kawasaki, Takuro; To, Kentaro; Tsutsui, Noriaki; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru

Proceedings of 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2018) (Internet), 3 Pages, 2019/10

https://doi.org/10.1109/NSSMIC.2018.8824447

A two-dimensional scintillation neutron detector with a submillimeter spatial resolution was developed for pulsed neutron diffraction imaging at the J-PARC MLF. The detector comprised the thin, single ZnS/LiF scintillator screen coupled with the crossed wavelength-shifting fiber array for light collection. For a high spatial resolution, the wavelength shifting fibers with diameter of 0.1 mm were used them for assembling the detector. The prototype detector that has a neutron-sensitive area of 24 24 mm exhibited a spatial resolution of 0.200.06 mm and 0.160.06 mm for x and y directions, respectively. The detector had a detection efficiency of 7 for thermal neutrons with a Co -ray sensitivity in the order of 10. In this paper detailed detector design is presented together with experimental results using the pulsed neutron beam.