Target Commissioning

We should plan on finishing target installation no later than June but the present goal should be to have everything ready for a minimal target by the first week of May with the cave closed up.  FNAL needs 2 weeks dedicated to beam tuning with no access. The third week of April would be the soonest we could ask for the beam. We will likely still be fighting the target review but hope to be done by the first or second week of May.

Minimal target setup:

Filling with commercial dewars or not: The main helium gas intake manifold is designed so that it is relatively easy to connect high purity commercial gas bottles, compress it and store it. If we fill the magnet and have enough to store for at least two other fills then we can prepare to run a very minimalist target system to have some beam on target. I point this out incase it becomes relevant for us or either agency down the road.  It's better if we can figure out a FNAL protocol for storing additional LHe in the Hall or filling with LHe from a delivery.  The QT system can produce 200 L per day but our transfer is expected to be about 60% efficient.  The magnet holds 135 L but depending on the starting temperature of the coils the magnet fill can require significantly more than 135 L.  From about 80 K the fill would require about 300 L.  If it's kept at about 4K then you only need about 185 L to fill.  Right now we can only store a maximum of 500 L of liquid.  It would be possible to run a minimal target system (magnet and fridge) for a couple of days with even fewer electronics needed than what is listed in the critical path electronics. To polarize we need only a temporary microwave setup and polarization measurements.  To measure the polarization we need the UVA NMR running in the Hall storing data to the NMR local machine. For the minimal polarized target system with no running roots and no continuous running QT system one could get about 20% proton polarization achievable at any time of the year even if other parts of the system are not yet leak-tight and/or ready to run. This is also a reasonable mode to begin commissioning the target magnet.

Sealed QT Commissioning:

QT has its own setup and commissioning procedure which will take at least a dedicated two weeks. This can be done with everything closed/sealed from the QT system except the main helium gas intake manifold. If we want dedicated help with QT present for the transfer line testing we should be ready to also deliver liquid helium to the magnet at this point. If all piping is in place and the full system is sealed and we are able to spend all the necessary time in the Hall leak checking both the helium side and vacuum insulation side of the system and no leaks from any and all of the safety relieving parts are found then full commissioning of the circulating cryosystem can commence. I estimate this part of commissioning to take at least 4 weeks including leak checking and initial magnet fill.

PT Magnet Commissioning:

The first step here is to do a cooldown of the magnet and test to see what type of boil-off rate we are getting with the recent safety modifications and vacuum setup. This would normally take about two weeks of dedicated time and can be coupled to the refrigerator and/or fully sealed QT commissioning if fitting. This assumes no un-intended quenches or vacuum issues.

Beam-target Commissioning:

The next step is to see at what intensity we can actually run without quenching. This part has been previously outlined in the quench commissioning note. The focus is on finding the intensity threshold and would require completion of the critical path electronics for monitoring purposes. There would be a set of intended quenches done to understand and reproduce thresholds and study optimization of the magnet pumping cycle and present coil temperature regulation system. Geometry and materials of the target insert may need to be modified to get the lowest background rates. This may end up being different for NH3 and ND3. This part of the commissioning is expected to take about three weeks.  See Quench Commissioning

Initial Run-plan:

We should start with NH3 as it is much much easier to work with and easier to polarized and measure. There are several details to be worked out about the highest intensity and stable cryogenic operations as well as system monitoring that can only be worked out once everything is set up and running with an active polarized target system.  This phase of the run-plan I estimate to be about 3-4 months. We should be able to gain all the information we need on polarization decay and measurement as well as figure out whatever insert modification might be needed to limit background rates and monitor polarization with NMR coil geometry, etc… We should expect to flip polarization in a non-diurnal cycle in this initial run plan and attempt a few thermal equilibrium measurements.