Seamless Straw R

1
Seamless Straw RDStatus Report

• Akira Sato
• Osaka University
• MECO Collaboration Meeting
• BNL, 2-3 June 2003

2
Outline

• Tests of a straw with ground line
• PEEK straw chamber
• Al-ground-line-evaporated straw
• Future plan

3
To improve high rate tolerance

• avoid voltage drop
• Lower resistance straw
• more carbon
• make position resolution worse
• frangible
• Ground line
• 1) ground line along a straw
• Uniform position resolution
• Evaporated ground-line Large vacuum chamber is
  needed for long straw.
• 2) Connect ground line to some points on the
  straw.
• Lack of uniformity

4
Experimental setup

• a purpose of this experiment is to study the
  effects of ground line on the basic performance

• Induced charges Cathode strips
• Charge ratio method
• Position resolution

5
Experimental setup (cont.)
source and collimator
cathode pad
ASD Board
Conducting adhesive f2.5mm
PI straw
wire to ground
6
Induced Charges
without ground line

• Induced charges were lower around the grounded
  position.
• They were back to the original level when the
  position is more than 20 mm from the grounded
  position.

with ground line
ground point
7
Position by Charge ratio method
without ground line

• Maximum deviation is 0.55mm.
• It can be corrected.

with ground line
ground point
8
Position resolution
without ground line

• Dropping of the induced charges makes position
  resolution worse.
• .standard deviation 0.56mm
• Design goal ( s1.4mm) is achieved without the
  correction.

with ground line
ground point
9
Seamless PEEK straw

• Seamless PEEK straw
• Extrusion lower cost
• by Gunze
• We have 10 sample straws
• PEEKCarbon
• Resistance 11.5Mohm/sq
• Thickness 30mm
• Diameter 5.8mm
• A chamber has been constructed using a PEEK
  straw. Basic tests were done using 55Fe. It
  worked as well as polyimides one.

HV2.0kV
10
Al-ground-line-evaporated PEEK

• Al was evaporated on the PEEK straws to make
  ground line.
• A test chamber using these straws will be
  delivered to us by the end of July.
• We are planning high rate test.

11
Future plan at Osaka

• Seamless PI straw tube
• A graduate student is writing a NIM paper based
  on his Master thesis with results from the last
  beam test.
• High Rate Test
• Another graduate student is now designing a high
  rate test for the Al-ground-line-evaporated PEEK
  straw chamber. The test will be carried out in
  this summer or autumn.
• Prototyping
• The design of prototype-2 with new end-caps is
  aimed.
• Since we have no RD money to continue, financial
  support from the MECO collaboration is needed.
• Electronics
• The readout system using TMC (Time-Memory-Cell)
  has been build. Retrieving charge info from TDC
  using time-over-threshold will be studied by the
  end of June.
• Optimize the analog circuit for the high rate
  test.
• Develop the digital readout for the test.

12
End of Slides
13
Charge Ratio Method
avalanche

• Charge Ratio
• Calculate theoretical R by usingMirror Image
  Method.
• Prepare a map from R to position.
• Look up the map with observed R to get the
  position.
• deff (effective gap betweenpad and anode) was
  empiricallydetermined so that it givesthe best
  resolution.

Q-1
Q0
Q1
Position difference
deff