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Status of the Longitudinal and Transverse Polarimeters

Status of the Longitudinal and Transverse Polarimeters. Working polarimeters HERA polarization status 2005 Efficiency of the polarimeters TPOL & LPOL Cavity LPOL Energy spectrum with locked or unlocked cavity Bremsstralung spectra Present Status New calorimeter. WORKING POLARIMETERS.

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Status of the Longitudinal and Transverse Polarimeters

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  1. Status of the Longitudinal and Transverse Polarimeters • Working polarimeters • HERA polarization status 2005 • Efficiency of the polarimeters • TPOL & LPOL • Cavity LPOL • Energy spectrum with locked or unlocked cavity • Bremsstralung spectra • Present Status • New calorimeter Physics Research Commitee

  2. WORKING POLARIMETERS Physics Research Commitee

  3. Polarization Delivered in 2005 Helicity change Experiments wait that the Polarization level increase • Polarisation is rather low (less than 30%) compared to the previous year. • Polarization do not show a clear tendency. • Polarization level is not enough for experiments. For ex.HERMES predictions are based on 50%. Physics Research Commitee

  4. Efficiency of the Polarimeters TPOL ~94% LPOL ~91% Both ~98.25% • LPOL: Machine studies (begin of 2005) + Time for syst. studies and Cavity studies • TPOL: TPOL vacuum window + Hardware electronics. Physics Research Commitee

  5. LPOL & TPOL Physics Research Commitee

  6. LPOL CR=Crystal calo. SW= Sandwich calo. Good agrement TPOL-LPOL even at online level 2% errors between CR and SW. Detailed systematic studies are planned to decrease this number. Data from 1st Jan to 20th May show a clear agreement at online level (no LPOL data quality corrections) Physics Research Commitee

  7. TPOL Detailed syst. Studies shows beam spot to Polarization correlations. Monte Carlo simulation confirmed the observation. Focus correction now applied online to data: Applied on line Current TPOL syst. 3.5% • There were some changes in 2005 in hardware: • Stepping motor controler changed. • Si detector damaged 2 month ago- Debugging in progress. • Function generator for depol. Physics Research Commitee

  8. NEW CAVITY LPOL Physics Research Commitee

  9. Energy spectrum with locked or unlocked cavity 10/03/05 The new Cavity LPOL is recording Comptons event now • Histograms show a clear signal of compton photons above the Bremsstrahlung spectrum. • Estimation gives a rate of 0.1 photons per bunch crossing Physics Research Commitee

  10. Bremsstrahlung Spectra PM Voltage: 850V PM Voltage: 850V Ibunch=170A Ibunch =83,7A « shoulder » Brems Spectra is now understood • Synchrotron radiation shift has been reduced by putting a one X0 tungsten plate in front of the calo • Problems with electronics readout induced a « shoulder », now removed Physics Research Commitee

  11. 06/05/05 BREMS COMPTONS • Locking STABLE under any accelerator conditions. • Locking STABLE / switch laser pol. • DAQ problems, under study • Polarisation estimation almost there. Cavity LPOL is on the way to deliver polarisation Present status Physics Research Commitee

  12. New Calorimeter • Neither of the 2 LPOL calo are suitable for cavity operations. • Tungsten- Quartz fiber sampling calorimeter. • Signal produced from Č radiation in the quartz fiber. • 50 layers of tungsten plate interleaved with layers of quartz fiber Physics Research Commitee

  13. New Calorimeter Will be finished by end of June, take into operation as soon as possible • Design and complete simulation of Č light done • Energy resolution within the requirements • To do: Cut the fibers & bundle them. Physics Research Commitee

  14. Conclusions • Working polarimeters: • In 2005 Efficiency for the LPOL is ~ 91% and TPOL ~ 94%, combined 98.3% • TPOL & LPOL: • Polarimeters in agreement within systematics • Cavity LPOL: • Procedure for Laser/e-beam interaction now established • Brems. spectrum is understood. DAQ problems are under studies. • New calorimeter will be built by the end of June and put in operation immediately after. Physics Research Commitee

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