Radiation Exposure Tests in December for Hall A.

We will have three days of beamtime (Dec 3-5). We will use the the 25-MeV linac to direct an electron beam upon the PbF2 crystals. The Lead Flouride crystals will be placed on a translator table so that each crystal can moved individually into the beam. The crystals are 30x30x185 [math]\mbox{mm}^3[/math] and are 1290g each.

We need to keep the Power below 1 Watt onto the [math]\mbox{PbF}_2[/math]crystal or 0.78 Gy/s for a [math]\mbox{PbF}_2[/math] block of 1.3 kg. We can achieve this by setting the beam parameters of the 25-MeV LINAC (cf. http://www.iac.isu.edu/facilities/25MeV_hall.html).

Here we have: P = E [math]\times[/math] I [P] Watts, [E] MeV, and [I] [math]\mu[/math]A

Accelerator Settings

beam energy	20 MeV
Rep Rate:	10 Hz
I_peak:	50 mA/pulse
pulse width:	0.1 [math]\mu[/math]s (100 ns)

Time on for one second is 1 us. and Time off is 0.999999 s The average current 0.999999 * 0 + 0.000001*50mA = 0.05 [math]\mu[/math]A.

P = (20 MeV) [math]\times[/math] (0.05 [math]\mu[/math]A) = 1 Watt.

With the proviso, that we need to keep the I_peak (Instantaneous Current in the pulse) well above 5 mA so the it can be tracked by the pick-up coil. 50 mA/pulse will do the job.

Crew: Pierre Bertin, Tony Forest, Adrianne Spilker, Amine Mestari, Syed Naeem, and Phil Cole

Status of Setup.

 Translator Table (3 degrees of freedom).  
    Setup Done.  Amine and Adrianne
    DAQ/Readout
 Faraday Cups
    Setup
    DAQ/Readout
 Pickup Coil
    Setup 
    DAQ/Readout
 Lead Shielding

Day 0 will be for final setup. Pierre, Tony, and Adrianne.

Day 4 and Day 5 will be used to more curing and transparency measurements.

The specifics are listed below