Status of AT-TPC

Update of Prototype AT-TPC

May 6, 2010

Weekly meeting

Daisuke Suzuki, NSCL

Test room update

Completed

• Construction

• Clean room certification (class 1,000)

To do

Utilities

• Gas bottle stand installation (10 min job)

• Ethernet (Office, clean DAQ, control requested)

• Clean AC supply, clean DAQ network (2~3 months)

• Entrance space (work order needed)

On-going

• Pump exhaust connection

• Room key -> NSCL standard UB-4

Accessories

• Clean room cloths

• Stool, chair -> MSU surplus, local warehouse

Layout plan

Cabinet 2

Cabinet 2

Desk 02

Desk 02

Desk01

Desk01

Rack

Rack

Gas handler

Gas bottle

Desk04

Desk04

Scale = 40”/1”

Toolbox

Toolbox

Desk05

Desk05

12 ft

Utilities

Desk 03

Desk 03

45.5”

77.5”

17”

97”

12”

118.5”

21.5”

21”1/4

47”3/4

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\test_room\CIMG1723.JPG$

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\test_room\CIMG1720.JPG$

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\test_room\CIMG1719.JPG$

Test at the test bench; setup

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\atris\sap(2009-11-09)\presentation\CIMG1681.JPG$

10 x 10 cm2

w/ 17 strips

He + CO2 (10%) 1 atm, 241Am

$C:\Documents and Settings\suzuki\Desktop\Pictures\test_chamber_interior_2010-apr\SDC10850.JPG$

Cathode

α

New adopter board

• Mesh signal amplitude was very small.

• The adopter board and the T2K was not fully connected. The anodepads floated.

• Part of the PCB was cut off to improve the connection.

Vmesh = -350 V, Vcathode = - 1~2 kV; Amesh = - 60 mV (old) <-> -50 mV (new)

$C:\Documents and Settings\suzuki\Desktop\Pictures\CIMG1795.JPG$

$C:\Documents and Settings\suzuki\Desktop\Pictures\CIMG1797.JPG$

• Measured the resistance from the adopter input to the T2K ground

Old 100 M Ω <-> New > 1 GΩ

Old

New

Adopter

Negative cross talk

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\prototype\meeting\2010-04-22\waveform1.png$

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\prototype\meeting\2010-04-22\waveform2.png$

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\prototype\meeting\2010-04-22\waveform3.png$

$\\intranet.nscl.msu.edu\files\user\suzuki\My Documents\at-tpc\prototype\meeting\2010-04-22\waveform4.png$

$E:\Screenshot-9.png$

Run 202 He+CO2(30%) 1 atm, 241Am

Event 3

Time bin

ASIC Channel

α

• Cross talk signal with negative polarity

• Almost identical amplitude

0.1 mm

Measure

• High segmentation

-> Low Cpad/Ctot

• Put a capacitor between the mesh and the ground

<-> Damage risk during discharge

•Capacitive coupling among the anode pads

• Amplitude ~ Cpad/Ctot

STAR TPC NIM A499, 659 (2003)

• Pads are coupled by the mesh.

-> Cpad is independent on the distancebetween the associated pads

Wire plane

Micromegas

mesh

pad

F. Sauli, CERN/94-195, 1994

0.5 mm

Result

mesh

pad

Cadd

Cadd = 0

$C:\Documents and Settings\suzuki\Desktop\Pictures\test_2010-5-5\he_co2_30_hv_400.bmp$

$C:\Documents and Settings\suzuki\Desktop\Pictures\test_2010-5-5\he_co2_30_hv_400_wc2nF.bmp$

Cadd = 2 nF

The negative pulseamplitude reducedby factor of ~3

c.f. Measured capacitance ofMicromegas Ctot = 1.1~1.4 nF