Beam test results of the Intermediate Silicon Tracker for sPHENIX

Abstract

The Intermediate Silicon Tracker (INTT), a two-layer barrel silicon strip tracker, is a key component of the tracking system for sPHENIX at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The INTT is designed to enable the association of reconstructed tracks with individual RHIC bunch crossings. To evaluate the performance of preproduction INTT ladders and the readout chain, a beam test was conducted at the Research Center for Accelerator and Radioisotope Science, Tohoku University, Japan. This paper presents the performance of the INTT evaluated through studies of the signal-to-noise ratio, residual distribution, spatial resolution, hit-detection efficiency, and multiple track reconstruction.

Figures (11)

• Figure 1: The schematic drawing of the INTT barrel and a ladder. The active areas of the ladders are shown as cyan boxes. The coordinate system used for the sPHENIX experiment is also shown.
• Figure 2: The schematic drawing of an INTT ladder with sensors facing up. An INTT ladder consists of two types of silicon sensors, FPHX chips, HDI cables, and a CFC stave. The sensors are divided into 16 (Type-A) and 10 (Type-B) blocks read out by individual FPHX chips. A silicon block has 128 strips oriented horizontally with a pitch of 78µm and a length of 16$\rm \,mm$ (Type-A) or 20$\rm \,mm$ (Type-B). The coordinate system used in the beam test is also shown.
• Figure 3: The schematic diagram of the setup for the INTT beam test at RARiS. The INTT telescope, containing four evenly spaced INTT preproduction ladders, was located on the positron beamline. Two trigger scintillators were installed upstream and downstream of the INTT telescope, respectively. A fingertip-sized scintillator was placed in front of the upstream trigger scintillator, but its data was not included in the analysis. The x-, y-, and z-axes used in the beam test are also shown.
• Figure 4: The distribution filled by $r$ with $C_{\mathrm{L_{1}}}$ set to zero for a representative cell. The mean of the Gaussian function fitted to the distribution indicates the amount of misalignment of $\mathrm{L_{1}}$ relative to $\mathrm{L_{0}}$ and $\mathrm{L_{2}}$.
• Figure 5: The energy-deposit distribution, constructed by the eight sequential measurements (histograms with different colors) after applying scaling factors, for a representative ladder ($\mathrm{L_{0}}$).