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Argon Level Checklist Questions

There are two questions in the shifter checklist designed to note when (a) our Argon vendor (air products) tops up the external 500 Gallon dewer, and (b) when there is a top up of the cryostat from the external dewer.

LAr Level: Has there been increase in the liquid argon level in the 500 Gal external dewer since the last checklist?:

To check this, look at the variable uB_Cryo_IFIX_1_0/LT686 in slowcontrols. its is best to zoom out so that you are plotting a timeframe of a least a week. Sudden increases in this variable of magnitude > 10 signify a external top up. See the Blue trace in the plot below as an example topup of the 500 Gal dewer around the 28th December.

LAr Level: Has there been an increase in the uBooNE Cryostat LAr level since the last checklist?:

To check this, look at the variable uB_Cryo_IFIX_1_0/LT122_m in slowcontrols. its is again always best to zoom out so that you are plotting a timeframe of a least a week. Here there is usually more daily noise, but one is looking for a continued rise over the space of many hours, with a change in magnitude of at least 0.004. See the Red trace in the plot below as an example of a filling of the cryostat starting on 26th December.

Note that the external top up does not necessarily have to overlap with the cyrostat filling, but often does as in this example.