Calculating the time required for target room access:

            If NSRL is running in "dedicated" mode, i.e. without RHIC operating simultaneously, access is simpler and quicker.  If a sample exchange involves simply lifting out an earlier sample and placing a new sample, then times between exposures can be less than about 4 minutes.  This includes calling the MCR to release the key tree, getting an iris scan, pulling an interlock key, walking into the target room and switching samples, walking out of the target room, returning the key, performing another iris scan, and then waiting for the "Beam Immanent" alarm period to end and the interlocks to switch off.  In calculating beam time needs, users should use as a rule of thumb 4 minutes plus whatever is the planned exposure time at the exposure rate anticipated.  Contact the NSRL Liaison Physicist to verify that the dose rates used in an exposure calculation can be realistically achieved.

            If NSRL is running in "parasitic" mode, i.e. simultaneous to RHIC operations, then sample switching takes longer.  Typical sample changing times are 7-8 minutes plus exposure times.  This must be included in calculation of beam exposure times. 

Users may take advantage of a Beam Time Calculator in order to determine how much beam time to request.  Simply open the spreadsheet, and fill in the boxes, and it will recommend a total beam time required.  Hovering over the questions displays a short explanation of the question.  You can get help calculating the average irradiation time by using the Average Irradiation Time Calculator (in blue) specifying the number of exposures and doses you plan to use.  When finished, then enter the average irradiation time into the box on the Beam Time Calculator worksheet.

Contact the NSRL Liaison Physicist if you have any questions concerning these issues.

 

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Last Modified: December 20, 2012
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