hlab meeting 2/17/09 k. shirotori. contents noise reduction for cyric experiment
TRANSCRIPT
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+12C → 12C+ppol
⇒ ppol+12C→12C+pscat
⇒ pscat measured
⇒LS force effect
• Test MPPC + Scifi active target• Study for us (staff, students)
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…?
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
Target room4Beam 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
▼
1 M
▼
1 M
0.1 F 0.1 F 0.1 F
MPPC
Bias HV
PMT amp PMT amp 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
VMEFrame
Vacuum
chamber
Beam line
AC100V
Cable (lemo)
Cable (flat)
Floor
Ground
Upstream of beam line
Connected
Disconnected
??
??
Electronics
⇒Frame ground
by ground ribbon
Target room4Beam 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
▼
1 M
▼
1 M
0.1 F 0.1 F 0.1 F
MPPC
Bias HV
PMT amp PMT amp PMT amp
Lemo
Common ground
⇒Beam line
Lemo
Frame
Flat cable (covered Al foil)
Ground ribbon
Ground
ribbon
Ground of bias circuit
▼
1 M
▼
1 M
▼
1 M
0.1 F 0.1 F 0.1 F
MPPC
Bias HV
PMT amp PMT amp 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 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 ….
圧縮
Before After