arXiv subjects

Weimin Pan

Publications and source records attributed to Weimin Pan.

11 recordsLinked to original sources

arXiv2026

Booster-based beam recycling for swap-out injection at the High Energy Photon Source

Fourth-generation synchrotron light sources employ ultralow-emittance storage rings with stringent injection requirements. On-axis swap-out injection alleviates the dependence on storage-ring dynamic aperture, but high-charge operation requires an efficient injector architecture capable of producing high-charge replacement bunches. This paper presents the accelerator physics design and performance analysis of a booster-based beam-recycling swap-out injection scheme implemented at the High Energy Photon Source (HEPS). In this approach, the full-energy booster serves as both an injector and a high-energy accumulator. An extracted storage-ring bunch is returned to the booster, merged with a low-charge bunch previously injected from the linac and accelerated to full energy. Following high-energy damping, the merged bunch is reinjected into the original storage-ring bucket. The scheme avoids the need for a dedicated accumulator ring while enabling high-charge bunch replacement. The recycling scheme was commissioned through staged machine studies. Full recycling-chain simulations, commissioning studies, and measured performance analysis are presented. The measured results characterize the recycling operation and quantify the transmission efficiency and performance limitations of the complete recycling loop. These results demonstrate the feasibility of the booster-based beam-recycling architecture and establish its operational basis for high-charge swap-out injection in future fourth-generation synchrotron light sources.

physics.acc-ph↗

arXiv2025

Cavity as Radio Telescope for Galactic Dark Photon

Dark photons, as a minimal extension of the Standard Model through an additional Abelian gauge group, may propagate relativistically across the galaxy, originating from dark matter decay or annihilation, thereby contributing to a galactic dark photon background. The generation of dark photons typically favors certain polarization modes, which are dependent on the interactions between dark matter and dark photons. We introduce a framework in which a resonant cavity is utilized to detect and differentiate these polarizations, leveraging the daily variation in expected signals due to the anisotropic distribution of dark photons and the rotation of the Earth. We conduct an experimental search using superconducting radio-frequency cavities, noted for their exceptionally high quality factors, proving them to be effective telescopes for observing galactic dark photons. This approach establishes the most stringent limits yet on the kinetic mixing coefficient between dark photons and electromagnetic photons, thereby unveiling a novel avenue for the indirect search for dark matter via multi-messenger astronomy.

hep-ph↗

arXiv2024

First Scan Search for Dark Photon Dark Matter with a Tunable Superconducting Radio-Frequency Cavity

Dark photons have emerged as promising candidates for dark matter, and their search is a top priority in particle physics, astrophysics, and cosmology. We report the first use of a tunable niobium superconducting radio-frequency cavity for a scan search of dark photon dark matter with innovative data analysis techniques. We mechanically adjusted the resonant frequency of a cavity submerged in liquid helium at a temperature of $2$ K, and scanned the dark photon mass over a frequency range of $1.37$ MHz centered at $1.3$ GHz. Our study leveraged the superconducting radio-frequency cavity's remarkably high quality factors of approximately $10^{10}$, resulting in the most stringent constraints to date on a substantial portion of the exclusion parameter space on the kinetic mixing coefficient $ε$ between dark photons and electromagnetic photons, yielding a value of $ε< 2.2 \times 10^{-16}$.

hep-ex↗

arXiv2023

High Q and high gradient performance of the first medium-temperature baking 1.3 GHz cryomodule

World's first 1.3 GHz cryomodule containing eight 9-cell superconducting radio-frequency (RF) cavities treated by medium-temperature furnace baking (mid-T bake) was developed, assembled and tested at IHEP for the Dalian Advanced Light Source (DALS) and CEPC R&D. The 9-cell cavities in the cryomodule achieved an unprecedented highest average Q0 of 3.8E10 at 16 MV/m and 3.6E10 at 21 MV/m in the horizontal test. The cryomodule can operate stably up to a total CW RF voltage greater than 191 MV, with an average cavity CW accelerating gradient of more than 23 MV/m. The results significantly exceed the specifications of CEPC, DALS and the other high repetition rate free electron laser facilities (LCLS-II, LCLS-II-HE, SHINE, S3FEL). There is evidence that the mid-T bake cavity may not require fast cool-down or long processing time in the cryomodule. This paper reviews the cryomodule performance and discusses some important issues in cryomodule assembly and testing.

physics.acc-ph↗

arXiv2021

Parasitic modes suppression in CW cold tests of 1.3 GHz 9-cell high Q cavities at IHEP

The CW RF test of 1.3 GHz 9-cell cavity in liquid helium bath at 2 K is a very important key point in the cavity procurement. Some problems can be found through the test, according which to optimized and improve the process of cavity. Recently, Medium temperature (mid-T) furnace bake of 1.3 GHz 9-cell cavities have been carried out at IHEP. Through the proceed of mid-T bake, the quality factor of cavity has been greatly improved. While the excitation of the parasitic modes in the high Q cavities CW cold test has been encountered, which implies an error source for the cavity gradient and quality factor determination. In order to ensure the testing accuracy of superconducting cavity, we have improved the testing system. Finally, the parasitic mode is completely suppressed and the CW RF cold test of high Q cavity is guaranteed.

physics.acc-ph↗

arXiv2020

Medium-temperature furnace bake of Superconducting Radio-Frequency cavities at IHEP

Recently, heat treatment between 250 C and 500 C has been attempted to improve quality factor of superconducting radio-frequency cavities at FNAL and KEK. Experiments of such medium temperature (mid-T) bake with furnaces have also been carried out at IHEP. Firstly, eleven 1.3 GHz 1-cell cavities were treated with different temperatures at a small furnace. The average quality factor has reached 3.6E10 when the gradient is 16 MV/m. Then, the recipe of mid-T furnace bake at 300 C for 3 hours has been applied to six 1.3 GHz 9-cell cavities at a new big furnace. The average quality factor has reached 3.8E10 when the gradient is 16 MV/m.

physics.acc-ph↗

arXiv2017

Commissioning of te China-ADS injector-I testing facility

The 10 MeV accelerator-driven subcritical system (ADS) Injector-I test stand at Institute of High Energy Physics (IHEP) is a testing facility dedicated to demonstrate one of the two injector design schemes [Injector Scheme-I, which works at 325 MHz], for the ADS project in China. The Injector adopted a four vane copper structure RFQ with output energy of 3.2 MeV and a superconducting (SC) section accommodating fourteen \b{eta}g=0.12 single spoke cavities, fourteen SC solenoids and fourteen cold BPMs. The ion source was installed since April of 2014, periods of commissioning are regularly scheduled between installation phases of the rest of the injector. Continuous wave (CW) beam was shooting through the injector and 10 MeV CW proton beam with average beam current around 2 mA was obtained recently. This contribution describe the results achieved so far and the difficulties encountered in CW commissioning.

physics.acc-ph↗

arXiv2015

Design of a 325MHz Half Wave Resonator prototype at IHEP

A 325MHz beta=0.14 superconducting half wave resonator(HWR) prototype has been developed at the Institute of High Energy Physics(IHEP), which can be applied in continuous wave (CW) high beam proton accelerators. In this paper, the electromagnetic (EM) design, multipacting simulation, mechanical optimization, and fabrication are introduced in details. In vertical test at 4.2K, the cavity reached Eacc=7MV/m with Q0=1.4*10^9 and Eacc=15.9MV/m with Q0=4.3*10^8.

physics.acc-ph↗

arXiv2014

Design and test of frequency tuner for CAEP high power THz free-electron laser

Peking University is developing a 1.3 GHz superconducting accelerating section for China Academy of Engineering Physics (CAEP) high power THz free-electron laser. A compact fast/slow tuner has developed by Institute of High Energy Physics (IHEP) for the accelerating section, to control Lorentz detuning, beam loading effect, compensate for microphonics and liquid Helium pressure fluctuations. The tuner design, warm test and cold test of the first prototype are presented.

physics.acc-ph↗

arXiv2013

The study and design of RF coupler for Chinese ADS HWR Superconducting Cavity

RF power coupler is a key component of the superconducting accelerating system in Chinese ADS proton linac injector I, which is used to transmit 15kW RF power from the power source to the superconducting HWR cavity. According to the requirement of working frequency, power level, transmission capability and cooling condition, the physics design of coupler has been finished, which includes RF structure optimization, thermal simulation, thermal stress analysis and so on. Based on this design, the prototype of HWR coupler has been fabricated, and then has passed the high power test successfully.

physics.acc-ph↗

arXiv2013

Coupler Conditioning and High Power Testing of ADS Spoke Cavity

Power couplers, used in China-ADS proton linac injector I, are required to transfer 6kW RF power to the superconducting Spoke cavities. At present, first two couplers of coaxial design have been fabricated and accomplished high power test at IHEP. The test results indicated that couplers of this design are qualified to deliver 10kW RF power in continuous travelling wave mode. This paper described the coupler's room temperature test procedures and results, discussed the original high power test terminated due to serious out-gassing and after some modifications. In the final test, the couplers smoothly exceeded the design power level.

physics.ins-det↗