Minutes DRAGON meeting July 24 2007
present:  UG, CR, MT, DH, AG, MJ, PM, AH, CV (recorder)

0) Minutes - very good

1) Hardware

   Mitutoyo: top slider is scraping - must be fixed before moving.
     PM can fix it in 10 min without changing the slit position itself.
     The long-term solution for improved measurement would require some
     modifications with jigs, should be done before the next beam time in Sept.

   DSSSD: debugging again the ribbon cable orientation. Problem was the broken
     detector bias power supply which had intermittent problems with the leakage
     current. PS exchanged with an Ortec module (which doesn't seem to have a
     leakage current monitor). Problem, since Rob Hanson is retired, there is no
     person on site to repair electronic modules.
     Could buy Mesytec MHV-4 detector PS instead, CR will ask for a quote.

   DH: call from operators that the preamps borrowed by the Loveland group are
     ready to return.

2) alpha acceptance tests

   AG is doing beam envelope studies at BCM monitor positions. The plate of the
     BCM is acting as a top slit which is inserted step-wise until beam is clipped.
     The measurements are then compared with GEANT. Start with BCM4 after MD2.
     Rate at the DSSSD is lower now (15 instead of 23 cps in May; CR had 19 cps
     earlier this year). Maybe the source has moved inside the holder. We might
     have to check the alignment (rotation) again and mark it.
     Size of BCM plates unclear (2x2 cm**2 ? - seems to be to small, maybe inches?).
     If BCM4 is in, there are no counts in reality, but in GEANT (with 2x2 cm**2)
     there are some. BCM study should be finished by the end of the week.

     Next week, installation of vibrating wire in Q1 & Q2. Mounting needs some mods
     on the downstream side.

     Solar cell detector - final drawing is finished (plastic which holds the
     detector in the pipe and cable feedthroughs). Plan to use both DSSSD preamp
     boxes, not clear if we can use inverting and non-inverting chips at the same time.

3) Mods of DRAGON area

   CR proposed to use the area at DRAGON more efficiently. Make a small work area
     for PM and other work at DRAGON. Also, a small setup for detector testing
     (using the chamber in the detector facility). The area under the platform
     could be turned into a quiet area with a sound blocking vinyl cladding.
     Question of cost, heat (=sauna) and safety (fire) are still open, but others
     on site have done similar things. CR will ask.

4) AOB

   next Tue (July 31) student talks. AG and MJ will speak early afternoon.