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 [math]\mbox{PbF}_2[/math] crystals. The Lead Flouride crystals will be placed on a translator table so that each crystal can be 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 appropriately (cf. http://www.iac.isu.edu/facilities/25MeV_hall.html).

Here we have: P = E [math]\times[/math] I

Here, [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 we keep the I_peak (Instantaneous Current in the pulse) well above 5 mA (noise level) 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

RunPlan:

PbFl_RadTests-12-3-07

PbFl_RadTests-12-4-07

PbFl_RadTests-12-5-07

Transparency test

A Blue light (OSRAM 24W/67 made in italy) with a wavelength range from 410 to 460 nm is used to anneal the crystals after irradiation.

A spectrometer (Ocean Optics USB4000) with a wavelength range from 200 to 1100 nm is then used to measure the transparency of crystals after optical curing.

Features of Spectrometer:

o Max sensitivity 130 photons/count at 400 nm; 60 photons/count at 600 nm o Resolution of 0.3 (FWHM) o Intergration times ~ 10 microseconds to 65 seconds o 16 bit, 3 MHz A/D Converter

References:

NIM articles:

File:Achenbach NIM A416 1998 pg357.pdf

File:Achenbach NIM A465 2001 pg318.pdf

Private Communications

File:FEL IrradiationTests 8-25-07.pdf
File:TransmissionTestProcedure J.Roche 10-15-07.pdf
File:CalorimeterHeatingEquations.pdf

IAC LeadFlourideCherenkovCrystalTests

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