Detailed Steps for Tuning In-Flight Beams
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Overview of the steps for In-flight beam delivery
Once steps for degraded beam tuning have been completed and a good focus is found at the RAISOR midplane (Separate detailed sheet for this), the steps below can be used to help guide the identification and tuning of the secondary beam.
- Acquire information on primary/degraded beam tunes and prep for beam
- Ask for docs from operations on primary and degraded beam TOFs and the charge state and slit scan data to be loaded into BOX
- Acquire the final cup/collimator FC currents and any notes on degraded beam transmission
- Note down RAISOR slit settings (in particular the midplane vertical slits are key)
- Insert detector of choice, make sure HV and preamps are on and daq is alive w/ noise etc
- Getting a reference spectrum from the degraded beam (can be done at RAISOR exit or target depending)
- Cut back beam by x100 w/ slits (not RAISOR slits) first then insert all available attenuation (~x15 Million) + RAISOR Att if needed
- Place beam on detectors and slowly remove attenuation until rates are roughly >100 Hz & <500 Hz
- Take ref spectrum - optimize daq params and save the settings file as they should not be changed for the duration of the run
- Run the RAISOR midplane slits in to 2 - 3 mm gap and take another spectrum (better to have small slit spacing for BRho scans)
- Determine the RF Sweeper(R501)/R401 phases for degraded beam with known TOF
- Set degraded beam rate to few hundred Hz and get Grafana running
- Have operations turn on Sweeper to Voltage=2 and phase=0 to start (R401 is still off)
- Note: You already may see a reduction in the beam rate do not increase beam current to get back to few hundred Hz
- Set the increment step = 1 degree, operators hold down increment to scan over 360 noting the phase every 10 - 20 degree
- Document the phase that transmission is the highest
- Do smaller steps of ~1 degreed around the regions of the maxima (should be two that are similar one <180 one >180 deg)
- Leave Sweeper(R501) at optimal phase, increase amplitude to 3,4,5,6V to see if improvement in transmission, note the best value.
- Set Sweeper (R501) to optimal phase/amplitude
- Turn on R401 to phase = 0, amp ~ 1.1 or 1.2 (below 0.9 seems to give it issues locking up)
- First scan phase, then scan amplitude similar to Sweeper to find optimal R401 parameters, note the values.
- TURN OFF THE SWEEPER AND R401 FOR NOW (or maybe only needs to have V=0??)
- Should be back to the few hundred Hz rate as at the beginning
- Identify the secondary beam
- Incrementally scale the RAISOR / beam line magnets in 0.5-1% steps until 1% or so past expected scale value
- At each step, remove attenuation to achieve the 100-500 Hz rates and searching for the beam of interest
- Take a fixed time run with the daq to note rates / purities (Compass and Ryan's boxscore separately would be good to cross check things if needed).
- Generate cuts at each step to track the movement of the beam charge states etc.
- Identify the isotope of interest based on calculated energies or previous production of the isotope
- Calculate the rate of the isotope of interest as the pps / pnA [note: pnA value from FCA001 divided by q of primary beam]
- Optimize and transmit secondary beam
- Once beam is on peak scale factor, make sure operators have access to direct rate of secondary beam either via grafana
- Operators should optimize tune at desired location
- Repeat steps above at target station if first carried out at RAISOR exit
- primary beam - the beam species and charge state taken out of the source at the ATLAS energy requested
- degraded beam - the same beam species as the primary beam but at a different (lower) energy and most likely different (higher) charge state
- production target - the target put in place before RAISOR, e.g., Be foil or Gas Cell