1. Preliminary Results of the Test Run at SLAC Petra Hüntemeyer

2. This analysis based on... two weeks of data taking or 707 runs each with between 2500 to 5000 recorded ‘events’ or  2 million recorded ‘events’ gas fillings: air, nitrogen, air-nitrogen mixtures, ethylene pressures between 3 and 760 torr readout from one of two PMTs

3. Analysis variables are... gas type/mixture pressure gas flow bit beam charge signal in the signal tubes signal in the blind tubes HV applied to the PMT

4. Cut Flow

5. First Pass Data Signal PMT

6. First Pass Data Signal PMT

7. First Pass Data Signal PMT

8. First Pass Data Signal PMT

9. Background subtraction

10. Background Subtraction

11. Corrected Signal S corr = S raw - P ave - f eth  S blind S raw : raw signal P ave : average pedestal S blind : blind tube signal f eth : factor from S raw / S blind ethylene runs

12. Linear Region Definition of a range where signal vs beam charge behavior is linear

13. Yield Calculation Y = S corr  f conv / bc  acc / sen S corr : corrected signal [ADC counts] f conv : conversion factor, ADC counts to pC bc : beam charge [ e - ] acc : geometrical acceptance sen : sensitivity from calibration folded with Bunner spectrum

14. Calibration

15. Preliminary Result : Air

16. Uncertainties: Air (incomplete!)

17. Preliminary Result: N 2

18. Preliminary Result

19. How does this compare with earlier measurements? Kakimoto et.al, Nucl. Inst. And Meth. A372 527 (1996) Preliminary result from this test run @ 28.5 GeV: 5-6 photons per m per e -

20. Analysis Conclusions promising preliminary results from a first look at the data a large amount of data collected during test run remains to be analyzed and more detailed systematic studies have to be performed insights from test run and analysis serve as input for the preparation of the anticipated experiment at SLAC

21. Conclusions purpose of T461: test run for a more sophisticated experiment proposed at SLAC we observed PMT signals in coincidence with the beam whose features are consistent with fluorescence the enhancement of the pure nitrogen signal over that in air is consistent with what we expect from earlier fluorescence measurements we observed a non-linear behavior of the fluorescence signal versus beam charge in the excess of 2  10 9 e - we also observed a linear behavior below 10 9 e - a study of the blind tubes indicates that the beam halo related backgrounds are relatively small