1. E-165 (FLASH) Status
8:00am 6/12/2004

2. Thick Target Program
Primary goal is to measure the fluorescence light output at different stages of shower development
Uses electromagnetic shower from FFTB 28.5 GeV pulses to simulate air showers

3. Actual optical chamber with “dog leg”

4. Status as of 8am 6/12/2004
FLASH optical chamber with PMT N1-N6 ready for action
Response/Aperture of chamber mapped and demonstrated to be stable against mechanical flexing
Have been set up for neutron background tests using spare PMTs B1, B2 since Thursday evening

5. Last 24 hours No beam yet to FFTB:
BCS system continues to make progress into the wee hours of the morning… (Thanks!!!)
Some vacuum problems in FFTB last night which has since been fixed
Prognosis is for “medium” intensity beam (~109) into the FFTB over the weekend while work on the the low current BCS system continues

6. Options
If low current BCS system is ready we will proceed with neutron background tests
High Current beam over the weekend: we will position the “dog leg” (without the main optical chamber) with a shutter and no shielding to look at beam-induced backgrounds

7. Neutron Background Tests
Place test PMT in simplified lead shielding (but maintaining the 8” of thickness allowed)
Will measure time profile and intensity of beam-related background (suspected to be almost all neutrons)
Replace some lead bricks in the middle layers with polyethylene bricks and repeat measurement, in the anticipation that the polyethylene will attenuate background neutrons as predicted by FLUKA simulations (H. Vincke).

8. High Current Beam Background Run
REQUIRES NOTHING in the BEAM PATH itself!!!!
The beam background will allow us to make a thorough checkout of the PMTs, readout, and LED monitoring systems
Also will let us exercise the data handling system (export to collaborating institutions for monitoring) and online analysis

9. Monday? If BCS system work should continue into Monday:
May request “thin target” run at medium current (~109 electrons per pulse)
Alumina targets will be retracted
The center of the main optical chambers have 4” diameter holes with thin windows and will represent about the same amount of material as we had during the thin target run in 9/2003

11. We promise…
We will NOT take any action without prior approval from the laboratory (and BAS in hand!)
In any event we would prefer to see the BCS work completed and proceed with the neutron background studies as early as possible (what would you all like besides cheesecake?)

12. Many Thanks
Again: we cannot give enough thanks to the experts and our friends at the MCC for working late into the night to help us get going…
Your help and hard work is VERY appreciated by the FLASH group as a whole
Thank you thank you thank you….