HLab meeting 2/17/09 K. Shirotori

Contents Noise reduction for CYRIC experiment

Purpose To measure polarization of proton (Scifi-MPPC システムを用いた陽子陽子散乱断面積測定と左右非対称度の測定 ) –p+ 12 C → 12 C+p pol ⇒ p pol + 12 C→ 12 C+p scat ⇒ p scat measured ⇒ LS force effect Test MPPC + Scifi active target Study for us (staff, students)

Necessary to noise reduction MPPC gain is small : ~10 5 –Planned to use PMT amplifier ⇒ The noise is enhanced by PMT amp, too. –Difficulty of one photon separation from pedestal –Energy resolution –Common noise ⇒ Accidental trigger, Gomi data Weak point of detector system –Ground of bias circuit –Protection of electromagnetic wave No cover of bias circuit Flat cable between bias circuit and MPPC –Hand made…?

Basic concept Ground : Same ground level –Detectors, crates, electric circuit, HV Clear cabling –As simple as possible (beautiful cabling) Insulation –No ground loop Shield for weak points –Al foil method for flat cables

Environment at TR4 Noise source : Cyclotron magnet, RF, beam line magnet, vacuum pump, compressor, electric power supply… ⇒ Cannot be removed. *~20 kHz switching noise from cyclotron magnet +  All system (detector, electronics, cables) in Target room4 ⇒ To connect all ground to be same by ground ribbon *Ground loop Need to connect beam pipe (target vacuum chamber) to electronics –AC100V between beam pipe and electronics (floating ground) ⇒ Beam pipe to be ground or other common ground *Nose from Cyclotron Ground of electronics power supply is unknown. ⇒ Not used *Not used for Hyperball2 experiment (Ground loop or some noise appeared and switching noise ~20kHz) Ground rod in target room4 is connected to the beam pipe. ⇒ Not used *Not effective reduction for Hyperball2 situation and risk of ground loop

Target room4

Beam pipe Shield Vacuum chamber Beam from Cyclotrons Frame (isolated from floor) Bias circuit (Yaki-niku, Kameki-sushi) Detector (Scifi, MPPC) AC100V DAQ PC NIM VME Distribution board Turbo pump Unknown : Distribution board ground, beam line ground, beam line power supply, any untouchable device Hole

Bias circuit ▼ 1 M  ▼ ▼ 0.1  F MPPC Bias HV PMT amp

Set up principle Connect beam pipe to electronics –Shut out the risk of AC100V (Ground rod in target room4 is connected to the beam pipe) –Ground of electronics power supply is unknown. ⇒ Not used Connect between bias circuit and NIM&VME circuit by ground ribbon Carefully check the insulation (ground loop by lemo i-connector) Try and error around bias circuit (flat cable shielding, to connect beam line and lemo- connector by ground ribbon)

Set up NIM VME Frame Vacuum chamber Beam line AC100V Cable (lemo) Cable (flat) Floor Ground Upstream of beam line Connected Disconnected ?? Electronics ⇒ Frame ground by ground ribbon

Target room4 Beam pipe Shield Vacuum chamber Beam from Cyclotrons Frame (isolated from floor) Bias circuit (Yakiniku, Kameki-sushi) Detector (Scifi, MPPC) AC100V DAQ PC NIM VME Distribution board Cable (lemo) Cable (flat) Turbo pump Tako-ashi Unknown : Distribution board ground, beam line ground, beam line power supply, unknown device Hole

Ground of bias circuit ▼ 1 M  ▼ ▼ 0.1  F MPPC Bias HV PMT amp Lemo Common ground ⇒ Beam line Lemo Frame Flat cable (covered Al foil) Ground ribbon Ground ribbon

Ground of bias circuit ▼ 1 M  ▼ ▼ 0.1  F MPPC Bias HV PMT amp Lemo Common ground ⇒ Beam line Lemo Frame Flat cable (covered Al foil) Ground ribbon Ground ribbon

Noise reduced Noise : 20 kHz (switching) +  (maybe ground loop) One photon (after PMT map) : ~3 mV Noise : 20 mV ⇒ 1~2 mV (~2 Ge room) 理由 強固なグラウンド : 同相成分の除去 Cabling : No ground loop アルミ作戦 : ケーブルの遮蔽とグラウンド 強化 Sample of noise (almost reduced) To be continued ….

圧縮 BeforeAfter