1. Progress on Photon Beam and Simulation Part 1: active collimator Part 2: physics simulations Richard Jones, University of Connecticut GlueX collaboration meetingMay 20-22, 2004, Bloomington

2. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 2 Photon Beam: open issues for the TDR  photon source deformation of thin crystals improved mounting technique  tagging spectrometer conceptual design under revision [talk by J. Kellie] detailed field calculations available [P. Brindza] possible advance-purchase item  photon tagger instrumentation tagging microscope  photon beam instrumentation beam line shielding  beam position control photon beam polarimetry

3. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 3 I. Active collimator prototype  Tungsten pin-cushion detector used on SLAC coherent bremsstrahlung beam line in 1970’s technology developed at SLAC through several iterations, refined construction method reference Miller and Walz, NIM 117 (1974) 33-37 SLAC experiment E-160 (ca. 2002, Bosted et.al.) still uses them, required building new ones performance is known

4. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 4 Design was part of the senior project of Connecticut undergraduate Chris Gauthier

5. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 5 Basic design: tungten pins on tungsten wedges 12 cm5 cm

6. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 6 Manufacturing challenge: cutting the pins  challenges to overcome choice of material  too soft, pins bend and break during tool extraction  too hard, pins are brittle and break off how to mount pins in base plate  tungsten wire forced into holes – SLAC method 1  machined out of one piece using EDM – SLAC method 2  to the rescue: FSU physics machine shop have their own in-house EDM machine willing to try new things, come up with their own ideas based on drawings from Connecticut, built 2 wedges  raw tungsten – too brittle, pins too fragile  machinable tungsten (95%W, 5%Ni+Cu) – excellent result!

7. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 7 Courtesy of P. Eugenio

8. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 8 Prototype status and plans  Parts for a working prototype are assembled aluminum housing made in Connecticut machine shop one tunsten pin quadrant delivered by FSU data acquisition computer electronics purchased by Jlab and delivered to Connecticut  8-channel sampling ADC card (pci)  special preamplifier with pA sensitivity (2 channels)  Still needed to complete project tungsten pins to instrument opposing quadrant (from FSU) boron nitride insulating support (ordered by Jlab, expected 7/04) software to read out currents and filter noise (student project 7/04) couple days of parasitic time in Hall B during photon running

9. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 9 II. Physics simulations  Hardware development built and commissioned new GlueX simulations cluster at UConn  Software development (more about this on Friday) upgraded XML geometry database tools to Apache XERCES 2 worked with Curtis to update geometry description of CDC new tools to support use of XML schemas in place of DTD’s  Background studies prior background studies have focused on region upstream of target new information needed to assess design choices for vertex counter geometry for simulations proposed by Werner new results as of this week – more about this from Werner

10. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 10 GlueX simulation cluster  parts purchased by Jlab (GlueX R&D funds) 16 AMD 2800+ processors 8 AMD 64-bit opteron processors 1 GB ram per node 20 GB local disk storage per node 5 TB of shared disk storage $28K total cost (incl. rack + UPS)  collaboration access uses web interface (no logins) uses certificates for security browse results with paw ROOT support coming

11. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 11 Electromagnetic background study: preliminary results photon beam

12. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 12 background study: preliminary results photon beam

13. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 13 background study: impact profile

14. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 14 background study: origin of charges hitting vtx cylinder inner surface impactsouter surface impacts

15. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 15 background study: preliminary endcap impactsall charged hits over 1 MeV

16. Richard Jones, GlueX meeting, Bloomington, May 20-22, 2004 16 background study: preliminary  Latest results are new still have to be carefully checked removed vacuum pipe from region downstream of target accidentally the air that replaced it has no magnetic field!  Rates are very high downstream of target most important around hole in FDC, Cerenkov, TOF and LGD will set an upper limit on the attainable beam intensity rates far downstream of target sensitive to magnetic field, but Werner’s result is probably accurate for the vertex counter  Backgrounds in each forward detector must be checked important information for the TDR may affect design choices in VTX, FDC and Cerenkov