1. 1 Apr. 28, 2007 Test of the Pulse Height and Time Jitter for the IHEP Full-Size RPC’s with 8-m-Long Readout Strip Planes C. Lu, K. McDonald and W. Sands Princeton University

2. 2 Apr. 28, 2007 4-Layer RPC Stack

3. 3 Apr. 28, 2007 Planar Arrays of Chambers Mount chambers in 4 planes, staggered to maintain high efficiency. Readout in 4 quadrants with 9-m-long readout strips. All electronics at the edge of the array. Simplified mechanics of chamber mounting.

4. 4 Apr. 28, 2007 Effect on Efficiency Dead regions between adjacent chambers in one plane  3% reduction in efficiency of that plane (95%  92%). With staggering of different planes, correlated inefficiency between a pair of planes will be ~ 0.1%. 3 out of 4 trigger efficiency is 96.5% (down from 98.6%).

5. 5 Apr. 28, 2007 Readout via Long Transmission Lines Long readout strips act as transmission lines  signal quality independent of position if strips properly terminated. Lab tests confirm this (rest of this presentation). If strip width remains at nominal 25 cm, can reduce number of readout channels by factor of 4. (Or, can increase position resolution by factor of 4 if keep channel count the same.)

6. 6 Apr. 28, 2007 Test setup IHEP single gap RPC chamber Readout strip Rigid honeycomb panel (1/2” thick) Al sheet underneath of the honeycomb as ground shielding and strip signal return plane. Al foil to shield the 8m long strip plane.

7. 7 Apr. 28, 2007 Flexible readout strip band This is Belle readout strip band, can make large roll of this material.

8. 8 Apr. 28, 2007 Honeycomb panel ½” thick honey comb panel, very rigid, surprisingly its dielectric constant is ~3.8  0.

9. 9 Apr. 28, 2007 Signal shape R1=165 Ω,R2=38Ω RPC1 HV ON R1=165 Ω,R2=2Ω RPC1 HV ON R1=165 Ω,R2=12Ω RPC1 HV ON Terminator’s effect on the signal’s shape

10. 10 Apr. 28, 2007 Test TDC and ADC simultaneously Use CAMAC TDC and charge sensitive ADC modules to test the 8m long strip readout signal.

11. 11 Apr. 28, 2007 Meantimer Time spectrum The trigger counters are 1m long, therefore the TDC start signal has intrinsic time jitter. We use LeCroy Meantimer modules to eliminate this jitter. Two trigger counters are overlapped, their outputs enter the LeCroy meantimer, its output signal corresponds to the signal initiated at the middle of the counter. 10ns/division Input #1 of the meantimer Input #2 of the meantimer Triggered by output of the meantimer

12. 12 Apr. 28, 2007 Trigger counters at far end of the strip plane First we place the trigger counters at the far end of the readout strip plane. Near and far end trigger arrangements are shown below:

13. 13 Apr. 28, 2007 Screen capture of the strip signal 80ns/div 50mV/div The screen captures on the left show several sequentially captured trigger events w/o any other selection.

14. 14 Apr. 28, 2007 TDC and QDC spectrum We used a LeCroy TDC module and a Phillips QDC module to measure the time and charge spectrum of the full size RPC chamber. Put the trigger counters at the far end of the strip plane. The time jitter for a 1m long section of RPC is ~6.5ns

15. 15 Apr. 28, 2007 Trigger counters at near end of the strip plane Screen captures of strip signal for trigger counters at the near end.

16. 16 Apr. 28, 2007 TDC and QDC spectrum (1 ch = 0.125pC)

17. 17 Apr. 28, 2007 Peak sensing ADC module test results Change HV setting, keep other electronics system fixed, we can see that ADC peak is shifting towards right, and TDC peak is shifting towards left while raising HV from 7400V to 7800V. ADC calibration: PH(mV)=(ADC(mV)+31)/0.7

18. 18 Apr. 28, 2007 Correlation between ADC and TDC Plot the scatter plot of ADC vs TDC, we found that TDC is quite constant. It does not depend on the ADC reading:

19. 19 Apr. 28, 2007 OPERA RPC system uses 8m long readout strip plane, the following pages show few steps of their installation procedure and the dimension of their strip plane.