MWPC prototyping and testing of STAR inner TPC upgrade Shuai Wang, Shandong University for the STAR collaboration p PANIC 2017,Beijing September , 2017 PANIC2017 3/09/2017

Upgrade motivation of iTPC Upgrade components of iTPC Outline Upgrade motivation of iTPC Upgrade components of iTPC iTPC MWPC prototyping iTPC MWPC test with 55Fe X-ray Summary and Outlook PANIC2017 3/09/2017 Shuai Wang

RHIC Beam Energy Scan(BES) RHIC-BES key objective Mapping the features of the QCD phase diagram. Physical mechanism Heavy ion collisions allow to explore the QCD phase structure by varying the collision energy. RHIC-BES program (I->II) Goals Turn-off of QGP signatures Search for critical point First order phase transition Schedule BES-I completed 2010~2014 BES-II in 2019~2020 It Need detailed study of the key region. PANIC2017 3/09/2017 Shuai Wang

Why to upgrade STAR iTPC Inner TPC upgrade: Increase inner sector pad coverage from 20% to 100% Extend TPC acceptance from |η|<1 to |η|<1.5 Lower pT measured minimum limit from 125MeV/c to 60 MeV/c Improve the dE/dx resolution from 7.5% to 6.5% (|η|<1) PANIC2017 3/09/2017 Shuai Wang

STAR TPC geometry STAR-TPC,NIM A499(2003)659 Outer sector Inner sector PANIC2017 3/09/2017 Shuai Wang

iTPC MWPC upgrade content Produce and replace all 24 inner sectors Increase readout channels Renew all three wire frames New electronics for inner sectors Pad coverage 20%->100% Gain uniformity better than 10% Detection efficiency >98% PANIC2017 3/09/2017 Shuai Wang

iTPC MWPC production procedure PCB bonding Wire mounts installing Pining wire mounts Mounting wires Epoxying wires Soldering wires PANIC2017 3/09/2017 Shuai Wang

Wire winding for MWPC Anode wires: Shield wires: Gated grid: gold-plated tungsten wires 20um diameter, tension 0.5N accuracy requirement:±0.03N Shield wires: gold-plated beryllium copper wires 75um diameter, tension 1.2N Gated grid: Why wiretension is so important May influence the uniformity of the gain Prevent the wire vibration under high voltage Three layers of wire for MWPC Winding machine at SDU PANIC2017 3/09/2017 Shuai Wang

Wire tension measurement system By the fast Fourier analysis program FFT , the fundamental frequency f is extracted from the vibration signal When the length of wire L and linear density ρ are known, the wire tension can be calculated by the formula :T=4 ρ f2L2 PANIC2017 3/09/2017 Shuai Wang

Anode wire tension test result Some test results of wire tension Anode wire tension test result Xu Wang,Fuwang Shen,Shuai Wang,Cunfeng Feng,Changyu Li,Peng Lu,Jim Thomas, Qinghua Xu,Chengguang Zhu NIM 859(2017),page 90-94. “Design and implementation of wire tension measurement system for MWPCs used in the STAR iTPC upgrade” Measurement uncertainty: <1% Meet the tension accuracy requirements 0.5±0.03N. PANIC2017 3/09/2017 Shuai Wang

Wire pitch and height control Wire comb and pitch control Wire pitch and height control schematic diagram PANIC2017 3/09/2017 Shuai Wang

Testing system for iTPC at SDU Cooling fan for FEEs and RDO boards Temperature transmitter Pressure transmitter Amplifier + MCA Temperature and pressure transmitter Amplifier + MCA Radioactive source 55Fe X-ray transmission window 100 um PCB with graphite coating PANIC2017 3/09/2017 Shuai Wang

55Fe spectrum of a single wire Anode voltage: 1120V P10(Ar:CH4 = 9:1) Gas pressure: +2mbar Temperature: 27.3℃ Amplifier: A225+A206 MCA Data Total rate: ~2077 Gas gain: 2700 Energy resolution(FWHM): ~20% Main Peak Escape Peak PANIC2017 3/09/2017 Shuai Wang

Correcting temperature and pressure dependence Gain=ec0+c1T/P Wire number:98th Data collected in 10 days Gas gain versus : Gain=ec0+c1T/P Correction set:T=25℃ P=1013mbar Gas gain variation: before correction=17.7%, after correction=4.8% Measuring accuracy: ΔT= ± 0.05℃ ΔP= ± 0.05mbar Data for 180 hours Measuring accuracy: ΔT= ± 0.05℃ ΔP= ± 0.05mbar Data for 180 hours PANIC2017 3/09/2017 Shuai Wang

Gas gain uniformity Scan time : last 1 day Before correction 8.6% After correction 6% Scan time : last 1 day The gain are corrected to 25℃, and the pressure corrected to 2mbar above the standard atmospheric pressure. Gain variation:6%(Max-Min),1%(RMS) PANIC2017 3/09/2017 Shuai Wang

Anode voltage scan Measured gain under different anode voltage Gain Vs HV follow the exponential distribution The peak position ratio of main peak to escape peak decrease from1.95 to 1.65 Temperature: 25.3℃-25.8℃ PANIC2017 3/09/2017 Shuai Wang

Thanks! Summary and Outlook iTPC mass production for STAR started in June 2017,and it is expected to be finished in August 2018 on schedule. Winding machine, Wire tension measurement system,and the test system for iTPC has been set up. Wire tension and other technical parameters all meet the requirements. The iTPC performance test with 55Fe for the first two sectors are completed. The uniformity met the requirement too. Thanks! PANIC2017 3/09/2017 Shuai Wang