Huizhou Hadron Spectrometer -- a Proposed High-rate Experimental Setup at the High Intensity Heavy-ion Accelerator Facility

TL;DR

This work proposes the Huizhou Hadron Spectrometer (HHaS) at the High-Intensity Heavy-Ion Accelerator Facility (HIAF) to exploit ultra-high beam intensities for precision hadron and nuclear physics. It presents a conceptual design combining a 1.5–4 T solenoidal magnet, a five-dimensional MAPS pixel tracker, LGAD TOF (~30 ps), and ADRIANO-II dual-readout EM calorimetry to enable triggerless, high-rate data acquisition with broad acceptance. The anticipated performance targets ~1% momentum resolution and ~3% EM energy resolution at 1 GeV, ~99% track efficiency, and rates up to ~100 MHz (proton) and ~1 MHz (heavy-ion), enabling extensive eta physics, BSM searches, hadron spectroscopy, hypernuclei studies, and QCD phase diagram exploration. If realized, HHaS could significantly accelerate medium- and high-energy physics research in China by delivering vastly increased statistics and comprehensive particle identification across multiple species.

Abstract

The High-Intensity Heavy-Ion Accelerator Facility (HIAF), currently under construction in Huizhou, Guangdong Province, China, is projected to be completed by 2025. This facility will be capable of producing proton and heavy-ion beams with energies reaching several GeV, thereby offering a versatile platform for advanced fundamental physics research. Key scientific objectives include exploring physics beyond the Standard Model through the search for novel particles and interactions, testing fundamental symmetries, investigating exotic hadronic states such as di-baryons, pentaquark states and multi-strange hypernuclei, conducting precise measurements of hadron and hypernucleus properties, and probing the phase boundary and critical point of nuclear matter. To facilitate these investigations, we propose the development of a dedicated experimental apparatus at HIAF - the Huizhou Hadron Spectrometer (HHaS). This paper presents the conceptual design of HHaS, comprising a solenoid magnet, a five-dimensional silicon pixel tracker, a Low-Gain Avalanche Detector (LGAD) for time-of-flight measurements, and a Cherenkov-scintillation dual-readout electromagnetic calorimeter. The design anticipates an unprecedented event rate of 1-100 MHz, extensive particle acceptance, a track momentum resolution at 1% level, an electromagnetic energy resolution of ~3% @ 1 GeV and multi-particle identification capabilities. Such capabilities position HHaS as a powerful instrument for advancing experimental studies in particle and nuclear physics. The successful realization of HHaS is expected to significantly bolster the development of medium- and high-energy physics research within China.

Figures (9)

• Figure 1: HHaS conceptual design.
• Figure 2: Estimated momentum resolution as a function of transverse momentum for $\pi^{\pm}$ and protons at different polar angles, with 1.5 T (upper panel) and 4 T (lower panel) magnetic fields. The $p_{\rm T}$ resolution from hit position resolution alone is shown by the dashdotted line.
• Figure 3: n$_\sigma$ separation as a function of transverse momentum for various charged particles at different polar angles using TOF measurements.
• Figure 4: $p_{\rm T}$ vs. $\theta$ distributions for $\pi^{\pm}$, $K^{\pm}$ and proton produced with top-energy proton and uranium beams at HIAF from GiBUU Buss:2011mx simulation, comparing with the $p_{\rm T}$ for 4-$\sigma$ and 6-$\sigma$$\pi$-K and K-p separation.
• Figure 5: $p_{\rm T}$ vs. $\theta$ distribution for $\pi^{\pm}$ from $\eta\rightarrow\pi^{+}\pi^{-}\pi^{0}$ decay, for the $\eta$ meson produced by a proton beam with a kinetic energy of 1.8 GeV bombarding a $^{7}Li$ target, comparing with the $p_{\rm T}$ for 4-$\sigma$ and 6-$\sigma$$\pi$-K separation.