Draft:LANL Microtron

The microtron at Los Alamos National Laboratory (LANL) in Los Alamos, New Mexico US was originally designed as a medical therapy machine, but since 2001 it has been used for non-destructive radiography of thick objects and R&D. This particular Microtron operates at 4 tunes with nominal energy endpoints of 6, 10, 15, and 20 MeV producing ~ 780, 1800, 2700, and 2800 R/min at 1 meter from the source

In 2018, a study was done using the Microtron to examine the performance of large-panel cerium-doped lutetium yttrium silicon oxide (LYSO) scintillators 3, 5 and 10 mm thick. The system resolution was measured and compared between the various end-point energies and scintillator thicknesses.

Microtron Slow Start Warm Up: A slow start consists of turning the PFN down and the aux gun down before you Trig On. Open up the two Scandinova windows for E1 and M1 so that you can see the voltage set point and voltage reading. Press Servo Off on Cab B and press Trig On at 6 MeV. While watching the oscilloscope and the voltage read out, slowly raise the high voltage until you get to the set point. Keep an eye on the vacuum as well throughout this process. For the voltage set point: E1 is 1175 volts and M1 is 1144 volts. If the machine shuts off while you are raising the PFN, try lowering the PFN and pressing Trig On. Once you get to the set points, use Channel 2 to adjust the aux gun value until reflective power is just above the magnetron signal on the oscilloscope.

MOD fault: If you are trying to turn on High Voltage, and get a red MOD fault on the screen, try resetting the modulator cabinet. Flip the switch on the right side of the cabinet and wait a minute then flip back on. Once your back at the computer, press reset on the upper left side and try turning on high voltage again.

MMPS fault: try to reset the MMPS in the back of cabinet B. The screen on Cab A should shut off and then after this you can flip the switch again to turn back on.

TRU fault: If the machine shuts itself off and you see the TRU is red on the screen and that reflective power is lit up on Cab B. First open the "TRU" panel on Cab B and press AFC off. Press the microwave frequency button and adjust the up and down switches that are next to the microwave frequency button. While adjusting, look at the reflective power on the oscilloscope. If when adjusting, you get a limit light on Cab B, try turning off the machine then adjusting the controls and turning the machine back on.

Interlock at the Roll Up Door: If you Trig On and see nothing on the oscilloscope, turn the machine off and check the roll up door to check if that interlock is engaged.

Dose Output is Lower than Expected: If you're at a certain energy and are not getting the dose output you normally would on the rad cal, adjust the circ coil until you see the dose output is improving or getting the expected range.

Beam Line Valve Closed: You can see if the beam line is open or closed under the "Water/Vac" tab. For this, turn the two knobs on the vacuum pump (the pump on the far side of the cage door to the Microtron). The two knobs are close to the beam line, and one will be turned 90 degrees. After this, press open under the Water/Vac tab. Once this is done, you can go back and close the valves on the pump.