HLab meeting

1. HLab meeting 2/17/09 K. Shirotori

2. Contents • Noise reduction for CYRIC experiment

3. 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+12C → 12C+ppol ⇒ ppol+12C→12C+pscat ⇒ pscat measured ⇒LS force effect • Test MPPC + Scifi active target • Study for us (staff, students)

4. Necessary to noise reduction • MPPC gain is small : ~105 • 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…?

5. 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

6. 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 + a • 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

7. Target room4

8. Target room4 Beam from Cyclotrons Beam pipe Vacuum chamber Turbo pump Frame (isolated from floor) Detector (Scifi, MPPC) Hole Bias circuit (Yaki-niku, Kameki-sushi) NIM VME Shield Unknown : Distribution board ground, beam line ground, beam line power supply, any untouchable device DAQ PC Distribution board AC100V

9. MPPC ▼ ▼ ▼ 1 MW 1 MW 1 MW Bias HV 0.1 mF 0.1 mF 0.1 mF Bias circuit PMT amp PMT amp PMT amp

10. 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)

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

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

13. MPPC ▼ ▼ ▼ 1 MW 1 MW 1 MW Bias HV 0.1 mF 0.1 mF 0.1 mF PMT amp PMT amp PMT amp Ground of bias circuit Flat cable (covered Al foil) Lemo Ground ribbon Frame Lemo Groundribbon Common ground ⇒Beam line

14. MPPC ▼ ▼ ▼ 1 MW 1 MW 1 MW Bias HV 0.1 mF 0.1 mF 0.1 mF PMT amp PMT amp PMT amp Ground of bias circuit Flat cable (covered Al foil) Lemo Ground ribbon Frame Lemo Groundribbon Common ground ⇒Beam line

15. Noise reduced • Noise : 20 kHz (switching) • + a (maybe ground loop) • One photon (after PMT map) • : ~3 mV • Noise : 20 mV⇒1~2 mV • (~2 mV @ 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 ….

16. 圧縮 Before After