At the J-PARC muon g-2/EDM experiment, a silicon strip detector will be used to detect positrons from muon decay. The detector consists of planes of detector modules arranged radially. The expected maximum hit rate reaches 1.4 MHz per sensor strip, and achieving high detection efficiency even under such hit-rate conditions is a key performance requirement. We have developed the smallest unit of the detector module, and its performance was evaluated using a muon beam at the J-PARC MLF H-line. The specifications of the detector module and the evaluated hit-rate capability are described in this article.

The muon g-2/EDM experiment at J-PARC is designed to precisely measure the muon's magnetic moment and electric dipole moment, driven by discrepancies between theory and previous experiments. One of the key challenges in the experiment is the fast reconstruction of positron tracks from multiple muon decays within a short time span causing an event pileup. Results from simulation studies have shown expected results in terms of efficiency and accuracy of track reconstruction. However, the execution time for the entire analysis chain is prohibitively long to be deployed in the experiment. Specifically, preliminary estimations suggest a requirement of 10 & times; speedup of the track-finding routine. In this context, we explore a GPU-based solution to accelerate track-finding through parallel processing and present the implementation details and the results of our study for different pileup conditions. The results indicate that the GPU solution meets our expectation in terms of execution speed without compromising on the reconstruction efficiency.

This study develops a new current-readout technique capable of handling measurements with high count rates reaching 1 Gcps. By directly capturing the output current of a photomultiplier as a digitized waveform, we estimate event rates, overcoming the limitations imposed by pulse pileup constraints and deadtimes. This innovative method is applied to a muon spin rotation/relaxation/resonance experiment at the Japan Proton Accelerator Research Complex, demonstrating its expected performance. Furthermore, we explore methods for estimating statistical uncertainty and investigate potential applications in analog-logic OR/AND gates. Our findings reveal that the developed technique opens avenues for developing future nonbinary logic circuits operating based on $n$-adic numbers.

A three-dimensional spiral beam injection scheme\* has been developed since 2014. This scheme is for accumulating a charged particle beam with relativistic energy in a sub-meter storage ring to realize for the J-PARC Muon g-2/EDM experiment (E34). Prior to the E34 experiment, we conducted a demonstration experiment utilizing 80 keV pulsed electron beam generated by an electron gun\**. The beam passed through a transport line of three rotating quadrupoles and was accumulated in an 80gauss solenoid magnet at the center fiducial volume with a diameter of storage orbit only 24cm. Now we have successfully accomplished (1) a strongly X-Y coupled beam phase space to inject into the axisymmetric solenoid magnetic field, (2) a weak focusing magnetic field potential within the storage region at the center of the solenoid magnet, (3) a pulsed magnetic field kick to guide the beam trajectory into the storage region, and (4) beam diagnosis in the storage area. In this presentation, we will report the experimental results of successful storage in an ultra-compact ring, and improvements for the actual storage ring for E34 based on this knowledge gained from 10 years of demonstration experiments.

The jet cross section and jet-substructure observables in p +p collisions at root s =200 GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-k(t) algorithm with a jet radius of R =0.3 for jets with transverse momentum within 8.0 < p(T) <40.0 GeV/c and pseudorapidity |eta| <0.15. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction (z(g)), charged-particle transverse momentum with respect to jet axis (j(T)), and radial distributions of charged particles within jets (r). Also measured was the distribution of xi =-ln(z), where z is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculations, the pythia and herwig event generators, and to other existing experimental results. Indicated from these measurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.

At the Japan Proton Accelerator Research Complex (J-PARC), low-emittance muon beams with a linear accelerator (linac) are proposed as a new approach to precisely measure the anomalous magnetic moment and electric dipole moment of the muon. Low-emittance muon beams can also be employed as new probes for non-destructive imaging techniques to see through structures. In the low-velocity section of the muon linac, a radio-frequency quadrupole linac (RFQ) and an interdigital H-mode drift tube linac (IH-DTL) are used to accelerate muons to β = v/c =0.08 and 0.28, respectively, at an operating frequency of 324 MHz. To reduce construction costs, the IH-DTL employs the alternating phase focusing (APF) method, which uses the transverse focusing force derived from the RF electric field. Because the APF method limits the transverse and longitudinal acceptances simultaneously, careful beam diagnostics and commissioning are essential to suppress the emittance growth derived from beam mismatches. In this paper, the results of the tracking simulation and the development status of the diagnostic and transport beamlines in the low-velocity section are described.

A three-dimensional spiral beam injection scheme* has been developed to realize very precise measurement of the muon spin precession frequency in the level of sub-ppm. A 300MeV/c muon beam is injected into a precisely adjusted storage magnet of sub-ppm uniformity by applying medical MRI magnet technologies for J-PARC muon g-2/EDM experiment. A strongly X-Y coupled beam is required to deliver beam into the storage volume via strong radial fringe field volume of solenoid magnet followed by beam injection channel through iron yoke**. A dedicated design work of reference trajectory and beam phase space has been made in this injection section. In this presentation, we show evaluated the tolerance for the accuracy of the reference trajectory and the orbital position dependence of the required X-Y coupling parameters and discuss the required accuracy of the transport line placed upstream of the beam-line which includes eight rotating quadrupoles on the 10m of beam transport line**. Additionally, a pair of dedicated magnets called active shield steering magnet will be set at the entrance and the exit of the beam channel to perform orbital correction of the reference trajectory.

In the J-PARC muon g-2/EDM experiment, a three-dimensional beam injection scheme will be adopted to inject a 300 MeV/c muon beam into a compact storage orbit. In this scheme, a low-emittance muon beam with X-Y coupling is injected from the edge of a solenoidal magnet and guided to a compact beam storage region where the magnetic field is precisely tunned for a muon g-2 measurement with a good systematic uncertainty. The method to design the injected beam phase space distribution was previously unclear, as muons pass through an area with a largely position-dependent, non-linear, and time-dependent magnetic field created by the solenoidal fringe field and kicker field during the injection process. This presentation introduces a new design method. By utilizing a linear approximation of beam transportation, an acceptance is defined for the injected beam distribution. This acceptance is represented as a three-dimensional hyperplane, allowing for a search of an optimal beam distribution by comparing it to beam phase space distribution candidates. The presentation reports the procedure and results of this method, as well as its limitations due to the assumed linear approximation.

A muon linear accelerator is under development at J-PARC for precise measurement of the muon anomalous magnetic moment (g–2) and electric dipole moment (EDM). A disk-and-washer (DAW) structure is employed to accelerate muons from 30% of the speed of light (kinetic energy = 4MeV) to 70% (40MeV) at 1296 MHz. The muon DAW consists of tanks accelerating the muons and bridge couplers that couple the tanks and focus the beam using an internal quadrupole doublet. A bridge-coupler prototype is currently being fabricated and will be tested. This paper presents the design and performance evaluation of the bridge coupler prototype.

We have been developing a compact pulse power supply with output pulse waveform specifications of 75kV/40A/50us/25Hz. This power supply is used to drive klystron for muon linac, which requires high stability and reliability. Next-generation power semiconductor SiC-MOSFETs with excellent characteristics of ultra-high breakdown voltage and low loss at 13kV, which were realized through the technological development of wide bandgap semiconductor devices, are used. Combining this SiC-MOSFET with the MARX circuit will realize a more compact pulse power supply with lower loss than conventional ones. In addition, it can be applied to portable accelerators in the future. In this presentation, the circuit design of the MARX power supply will be reported.

The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in root sNN = 200 GeV Au + Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by Levy-stable source distributions. The extracted source parameters are the correlation-strength parameter lambda, the Levy index of stability a, and the Levy-scale parameter R as a function of transverse mass m(T) and centrality. The lambda(m(T)) parameter is constant at larger values of m(T), but decreases as m(T) decreases. The Levy-scale parameter R(m(T)) decreases with mT and exhibits proportionality to the length scale of the nuclear overlap region. The Levy exponent alpha(m(T)) is independent of m(T) within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the Levy exponent a is significantly different from that of Gaussian ( alpha= 2) or Cauchy ( alpha = 1) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that, in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the eta meson is included. In each centrality class, the best value of the in-medium eta mass is compared to the mass of the. meson, as well as to several theoretical predictions that consider restoration of U-A(1) symmetry in hot hadronic matter.

In the J-PARC Muon g -2/EDM experiment, to measure muon anomalous magnetic moment ( g -2) and electrical dipole moment (EDM), it is necessary to accumulate 300MeV/ c muon beams with a 66 cm diameter region with a 3 T solenoid-type magnetic field. A new three-dimensional spiral injection scheme has been invented to achieve this target. Since this is the first instance to employ this injection scheme, a scale-down experiment with an electron beam of 297 keV/ c and storage beam diameter of 24 cm is established at KEK. A simplified storage beam monitor using scintillating fiber has been designed and fabricated to measure the stored beam. The 100 ns width pulsed beam is injected and the signal maintains a few microseconds by the stored beam observed. According to this result, the beam storage is confirmed. The recent result implies that the stored beam deviated from the design orbit and caused betatron oscillations. To measure the beam deviation quantitatively and tune the beam, the storage monitor has been updated. The data from this stored beam monitor are the primary data for considering the conceptual design of the beam monitor for the muon g -2/EDM experiment. This poster will discuss the measurement of beam storage by three-dimensional spiral injection and beam tuning using a scintillating fiber monitor.

The muon g-2/EDM experiment at J-PARC is designed to precisely measure the muon's magnetic moment and electric dipole moment, driven by discrepancies between theory and previous experiments. A key challenge is the fast reconstruction of positron tracks from multiple muon decays within a short time span causing an event pileup. One of the aspects is the identification of individual positron tracks from the reconstructed hits, which is currently done using a hough-transform based approach. Results from simulation studies have shown expected results in terms of efficiency and accuracy of track reconstruction. However, the execution time for the entire analysis chain is prohibitively long to be deployed in the experiment. Specifically, preliminary estimations suggest a requirement of 40 × speedup of the track-finding routine. In this context, we explore a GPU-based solution to accelerate track-finding through parallel processing and present the implementation details and the results of our study for different pileup conditions. The results indicate that the GPU solution far exceeds our expectation in terms of execution speed without compromising on the reconstruction efficiency.

The PHENIX experiment has performed a systematic study of identified charged-hadron ( p +/-, K +/-, p, p) production at midrapidity in p + Al, He-3+Au, and Cu + Au collisions at root s(NN) = 200 GeV and U + U collisions at root s(NN) = 193 GeV. Identified charged-hadron invariant transverse-momentum (p(T)) and transverse-mass (m(T)) spectra are presented and interpreted in terms of radially expanding thermalized systems. The particle ratios of K/ p and p/ p have been measured in different centrality ranges of large (Cu + Au and U + U) and small ( p + Al and He-3+Au) collision systems. The values of K/pi ratios measured in all considered collision systems were found to be consistent with those measured in p + p collisions. However, the values of p/pi ratios measured in large collision systems reach the values of approximate to 0.6, which is a factor of approximate to 2 larger than in p + p collisions. These results can be qualitatively understood in terms of the baryon enhancement expected from hadronization by recombination. Identified charged-hadron nuclear-modification factors (R-AB) are also presented. Enhancement of proton R-AB values over meson RAB values was observed in central He-3+Au, Cu + Au, and U + U collisions. The proton R-AB values measured in the p + Al collision system were found to be consistent with R-AB phi values of phi, pi(+/-), K-+/-, and pi(0) mesons, which may indicate that the size of the system produced in p + Al collisions is too small for recombination to cause a noticeable increase in proton production.

The SliT ASIC is a readout chip for the silicon strip detector to be used at the J-PARC muon g-2/EDM experiment. The production version of SliT128D was designed and mass production was finished. A quality assurance test method for bare SliT128D chips was developed to provide a sufficient number of chips for the experiment. The quality assurance test of the SliT128D chips was performed and 5735 chips were inspected. No defect was observed in chips of 84.3 Accepting a few channels with poor time walk performance out of 128 channels per chip, more than 90 the whole detector.

A strategy to design of a dedicated beam transport line for J-PARC Muon g-2/EDM experiment is described. To accomplish three-dimensional beam injection into the MRI-type compact storage ling, transverse beam phase spaces (X and Y components) should be coupled appropriately. We introduce a X-Y coupling, extended Twiss-parameters, and transfer-matrix of the entire transport line. We also discuss about detailed parameters of rotating quadruple magnets along the transport line.

J-PARC Muon Facility: MUSE (Muon Science Establishment) is responsible for the inter-university user program and the operation, maintenance, and construction of the muon beamlines, namely D-line, S-line, U-line, and H-line, along with the muon source at J-PARC Materials and Life Science Facility (MLF). In this paper, recent developments are briefly presented.

Two muon experiments, which require extremely homogeneous magnetic fields, are under preparations in J-PARC. One of the experiments is the MuSEUM（Muonium Spectroscopy Experiment Using Microwave）experiment that requires＋/-0.1 ppm homogeneity in a spheroidal volume of 20 cm in diameter and 30 cm in length. To confirm that such an extremely homogeneous magnetic field can be obtained in a whole-body MRI magnet, intensive shimming tests were conducted using a shimming calculation based on TSVD of linear algebra with a passive shimming structure. In the first shimming test, we found that small shim-piece unit is necessary, and in the second test an extremely homogeneous magnetic field was realized with Ni shim plates, the magnetic moment of which is 1/6 of the ordinal Fe shim plates of MRI magnetic field. This result confirms that an extremely homogeneous magnetic field can be realized for the experiment.

The disk-loaded structures (DLS) in the muon LINAC are under development for the J-PARC muon g–2/EDM experiment. Four DLSs with an accelerating gradient of 20 MV/m take charge of muon acceleration from 40 MeV to 212 MeV, which corresponds to 70% to 94% of the speed of light. The quasi-constant gradient type TM01-2π/3 mode DLSs with gradually varying disk spacing was designed and it was confirmed that the cumulative phase slip due to the mismatch between muon and phase velocity can be suppressed to less than 2 degrees at the frequency of 2592 MHz. In addition, the optimum synchronous phase and the lattice were investigated to satisfy the requirements of the total emittance less than 1.5π mm mrad and the momentum spread less than 0.1% in RMS.

The measurement of direct photons from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=39$ and 62.4 GeV in the transverse-momentum range $0.4<p_T<3$ Gev/$c$ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon $p_T$ spectra for different center-of-mass energies and for different centrality selections at $\sqrt{s_{_{NN}}}=62.4$ GeV is scaled with $(dN_{\rm ch}/d\eta)^{\alpha}$ for $\alpha=1.21{\pm}0.04$. This scaling also holds true for direct-photon spectra from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV measured earlier by PHENIX, as well as the spectra from Pb$+$Pb at $\sqrt{s_{_{NN}}}=2760$ GeV published by ALICE. The scaling power $\alpha$ seems to be independent of $p_T$, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to $p_T$ of 2 GeV/$c$. The spectra have a local inverse slope $T_{\rm eff}$ increasing with $p_T$ of $0.174\pm0.018$ GeV/$c$ in the range $0.4<p_T<1.3$ GeV/$c$ and increasing to $0.289\pm0.024$ GeV/$c$ for $0.9<p_T<2.1$ GeV/$c$. The observed similarity of low-$p_T$ direct-photon production from $\sqrt{s_{_{NN}}}= 39$ to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.