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Straw-Chamber R&D

Straw-Chamber R&D. M. Aoki, J. Ishii, Y. Kuno, A. Sakai, H. Sakamoto, A. Sato, S. Nakaoka, K. Nakahara, F. Maeda , T. Matsushima, R. Matsumiya Osaka university Y. Igarashi, T. Yokoi KEK. Based on F. Maeda’s Master thesis (2004). Stress. 1 atm. PEEK Seamless Straw Tubes.

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Straw-Chamber R&D

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  1. Straw-Chamber R&D M. Aoki, J. Ishii, Y. Kuno, A. Sakai, H. Sakamoto, A. Sato, S. Nakaoka, K. Nakahara, F. Maeda, T. Matsushima, R. Matsumiya Osaka university Y. Igarashi, T. Yokoi KEK Based on F. Maeda’s Master thesis (2004)

  2. Stress 1 atm PEEK Seamless Straw Tubes • Requirements on mechanical strength • Yield Stress > 10(MPa) • Young's modulus > 1.0(GPa) by assuming 1% swelling maximum • Radiation Dose > 100~200(Gy) • Polyimide(PI) • Outstanding mechanical strength • Good radiation tolerance • Not-easy to process; hard to make long tube • PEEK(PolyEther-Ether-Ketone) • Good mechanical strength and radiation tolerance • Thermoplastic: extrusion -> potential to make long tubes • Straightness?? vacuum Swelling < 1% PEEK tubes

  3. Straw Tube Samples Resistance (PEEK) Straightness (PEEK) X(mm) Tube L(mm) Accepted Distance along tube（mm) x/L

  4. Gas Ar：Ethane =50:50 Discriminator-Threshold:100mV PEEK PI PEEK chamber test • Plateau Curve • Continuous Operation • More than 1 week without trips at 1.8kV PEEK tube 55Fe HV ASD Buffer ASD Discriminator Scaler ASD:Amplifier-Shaper-Discriminator KEK ATLAS JAPAN ・gain ：0.8V/pC ・int. time ：16ns

  5. Comparison between 3 tubes • Objectives • Observe change of the resolution as the tube resistance changes. • Feedback the measurement to SPICE simulations, and find an optimum resistance of the tube. • Outline of Measurements • Compare the following measurements between three different tubes (700kW/sq., 3.3MW/sq., 8MW/sq.) • Cathode Charge Distribution • Spatial resolution from the cathode analysis

  6. Setup Top Gas Ar：Eth=50:50 Linear guide HV:1.60kV～1.7kV Tube Collimator(0.6mm) Sliding Stage Side 55Fe ASD DAQ

  7. Position Resolutions @1.7kV • Tube Dependence • No significant difference • The effect of the collimator is not corrected for. • HV Dependence • No dependence 700kW/sq. 8MW/sq.

  8. PI PEEK (8MW/sq.) (3.3MW/sq.) LAMINA (700kW/sq.) Charge Distributions • Comp. Between tubes • LAMINA - slightly broad • PEEK,PI - rather sharper↓ Because of this, the spatial resolution of PEEK was expected to be better than that of LAMINA, but the fact is not. • HV difference • Lower HV, Lower total charge • No change on the distribution shape ↓ Shape is motrh important than the total charge. LAMINA (700kW/sq.) PI(8MW/sq.) 1.7kV 1.65kV 1.6kV 1.7kV 1.65kV 1.6kV

  9. Ground Pattern Test for PEEK • Compare 3 tubes • No ground • 2mmt ground • Half-cylinder ground • Ground pattern • Vacuum evaporation • Aluminum • Thickness < 0.1mm 2mmt Half-Cylinder

  10. Measurements No ground • Total Charges • Decreases as the ground pattern widthincreases. • Charge Distributions • Sharper as the ground pattern widthincreases. • Resolution no ground ：0.60±0.03mm（R.M.S) 2mmt ：0.54±0.03mm(R.M.S) Half-Cylinder ：0.43±0.04mm(R.M.S) This trend might be explained by change of the charge distribution. • Need further studies by using computer simulations. 2mmt Half-cylinder

  11. PEEK Test Results • PEEK is usable as a straw tube of the gas chamber. • Plateau curve was measured. • Continuous operation over more than 1 week was succeeded. • Straightness might be a matter. • The effect of ground patterns was measured. • Charge distribution becomes sharper as the width of ground pattern increases. • Slightly better resolution as the width of ground pattern increases. • Need further studies with simulations

  12. A High Rate Test at KSR • Purpose • Understand the behavior of straw-tube chambers at a high rate environment. • Prove high-rate tolerance of the vacuum-evaporated tube chambers. • (Establish an alternative test facility other than KEK for detector developments in near future.)

  13. What we tested…. • We tried to see gas-gain drop of the tube chambers due to the HV drop by charge-up of the tubes. • The gas-gain was monitored by a charge in anode (ADC 2249W).

  14. Kyoto electron Storage Ring • Electrons : 60~100 MeV • slow extraction (a sort of) • Beam Spot : H-12mm, V-5mm

  15. Time Structure of the Beam • 1st level • ~sec • Control of slow extraction. • 2nd level • Several msec • Kicker modulation due to ripples of the AC power. • 3rd level • ~100 nsec • Kicker RF frequency • These are not serious problems for the high rate test.

  16. High Rate Test • A Scintillating Fiber trigger • Read anode charge by ADC 2249W • A tube length : 30 cm • Count beam rate by a scaler for each event as a rate monitor.

  17. Preliminary Results Without GP 50 kHz 400 kHz With GP 50 kHz 400 kHz

  18. Discussion • DC-like HV drop effect was hard to be observed. • A ground-patterned tube is better than the no-ground patterned tube. (need qualitative comparison) • We will try to repeat a beam test again with more careful arrangement.

  19. Other To Do List • Seek a possibility of doing high rate tests with radioactive sources? • Manufacture of long straight PEEK tubes • Development of Read-out electronics? • Front-end analog IC • TDC/ADC integrated chip (spin-out of Belle) • Interest to a specialist at KEK

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