CHIPS Run Feb-2008
Configure 25 Mev Beam line
1.5 inch FWHM beam profile measured at 8 mA peak current. The units on the beam scan is in inches. so the grid is 2inch by 2 inch (5cm by 5cm). Frequency is 60 Hz.
_________________________________ 4 mA peak current
Turned beam on zero degree port and NaI lights up whan positioned just after the beam pipe window.
Must be gammas Rate = 10 count/sec. Anode amplified (x64) then discriminated and put into a scaler. Threshold on discriminator is 2 Volts and results in zero counts when beam off. NaI PMT at 1500 volts.
Now move NaI detector so it is near experimental Cell wall. Just inside the wall
Gamma rate goes to zero!
Now change scope to 5 sec accumulation. 1 Mev electron should give 55 mV pulse on scope.
Now try to put electrons into Experimental cell.
We turned on the first dipole to deflect 10 MeV electrons onto the Tungsten target. The quads between the two dipoles were used to minimize the rates on the NaI. Then we turned on the last dipole to deflect 3 MeV electrons into the Experimental cell. And measured the following rates
811 counts /15 sec threshold at a minimim
Now insert 1.2 cm thick Aluminum plate in front of the NaI in order to capture all the electrons and measure the gamma rate.
776 counts /15 sec threshold at a minimim
Channel 6 : IAC NaI : Co-60 source gave 20 mV pulses on scope when PMT at 1200 Volts
Channel 10: JLab NaI : Co-60 source gave ~40 mV pulses on scope when PMT at 1400 Volts
Positron Runs with DAQ
Run 393: 1400 V JLAB NaI, 1209 Volts on ISU NaI, Trigger: (Gun AND NaI 1 ) OR (Gun AND NaI2), 50 mV Discriminator Threshold
Run 394: 1400 V JLAB NaI, 1209 Volts on ISU NaI, Trigger: (Gun AND NaI 1 ) AND (Gun AND NaI2), 50 mV Discriminator Threshold
Run 395: 1400 V JLAB NaI, 1209 Volts on ISU NaI, Trigger: (Gun AND NaI 1 ) AND (Gun AND NaI2), 30 mV Discriminator Threshold