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FACET FAQs

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GUIDE TO BEAMTIME

​FACET Specific User Instructions for Beam Time

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​How do I get approved for beamtime?

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Pre-shift requirements at FACET are:

1) a procedure for the beam time and
2) analyses of previous shifts.
 
This requirement is for the benefit of our user groups. Good planning leads to better results!
 
Users must have a written procedure for their beam time that clearly indicates the activity, requirements from the beam and operators and the time that is needed. Guidelines are given below (after Timeline).  
 
 
Timeline
 
Before the run gets scheduled
Coarse outlines including goals, expected analyses and beam and hardware requirements are expected in advance of the run so we can appropriately schedule the experiment. Please send these to the FACET User Manager. The step by step procedure is not required at this point but the sooner it is thought about, the better prepared you will be (it may be that only in thinking step by step, you will realise a missing piece of hardware or forgotten beam requirement).
 
The Coarse Outline is essentially the "Procedure" without part 2 (see section below on Procedure Guidelines).
 
Two weeks before scheduled beam time
The complete procedure for your beam time needs to be sent to Christine, Vitaly and Mark two weeks prior to the scheduled beam time and then it is expected to undergo reiteration closer to the shift itself.
 
If a group has multiple shifts or extensive periods for studies, then we don't need all procedures at once and indeed, one shift's experience often influences the procedure for the next shift. Therefore only the procedures for the first shift need to be sent. There is, however, little time between shifts to write procedures so they ought to be prepared.
 
In the week of beam time
The documents will be reviewed and discussed with the experimenters if necessary (and it is usually necessary!). If approved, the operator’s document will be forwarded by Vitaly or a designee to Jerry Yocky who schedules the beam time with the accelerator operations group. This is usually close to beam delivery due to the time it takes to reiterate the procedure.
 
The procedure will be agreed upon with FACET staff before beam time is handed over to the experiment. Often FACET staff will offer advice or request changes to the procedure which is why we need it in advance.
 
Procedure Guidelines
 
All procedures need to be headed with the expected date and time of the beam time.
  
1.      A clear definition of what constitutes that the beam is ready for delivery to a given experiment.
 
This is a set of requirements on the
a) beam (charge, orbit, location where spot size should be minimised, spot size, bunch length) and
b) required available diagnostics/hardware (TCAV…).
 
With regards beam parameters, explain what parameters are the critical ones. Give a tolerance where possible and indicate what is really essential to get any progress at all in the experiment and what is desirable to get the best data.
 
If you need it, ask for it, but if you don’t, don’t. We do not want to get in a habit of saying we need something and then saying “well, I guess that’s good enough, we’ll take it”. At the same time we don’t want to hold off an experiment tuning on a parameter that isn’t really needed.
 
Although not needed within the document, be prepared to justify the requirements from a physics perspective.
 
 
2.      A simple description of the measurements to be made, devices/parameters to be changed and rough durations.
 
Think of this as what you will go over with the operator before starting the measurements, e.g. “We will be measuring ___. To do this we will change ___. While we do this we need ___ to be monitored/held fixed. This will take approximately ____ hours.”
 
If the measurements require changing phases, magnets, waist locations etc it should be clearly listed.
 
 
3.      A plan for the experimenters themselves.
 
This is an outline/plan to help the experimenters be ready to take data efficiently and is an extended version of (2). This document is for you the experimenters. Although this document will benefit from review and discussion with FACET management (Vitaly, Christine, Mark), in the end this is ‘for you’.
 
 
4.      A definition of success.
 
This should define what subset of analysis will be completed quickly to understand what has been accomplished.
 
This analysis is important to present at the 8 o’clock meeting held at MCC as well as to communicate what has been seen with management and operations.
 
Think of this as a plot(s) or image(s) that are not (necessarily) ready for publication but can illustrate the data. This last point is important for two reasons:
1. Guide what changes, if any, are needed from the accelerator and
2. Discuss how much more beam time, if any, is needed to move forward or complete the measurement.
 
Please be somewhat specific as to the date/time analysis will be ready as that would help us schedule a meeting if one is required.
 
 
 
Example:


What do I do on the day of my beamtime?

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Day of beam time

Jerry Yocky or designee passes the procedure document for the operators on to the people on shift so they can set up the beam and check out the hardware as requested in the procedure.
 
Approx 1-2 hours before scheduled start of shift
Check in with your facility POC or MCC to ask what time delivery will begin. Sometimes the start of the shift can be delayed due to hardware issues that bring down the beam or make tuning difficult.
 
Start of Shift
Just before or at the start of the shift, you are requested to nominate a person in your group to act as the Point of Contact for communicating with Main Control/ the operators. This POC should talk through to procedure with the operator on shift for FACET so the operator has a good sense of how best to support the experiment.
 
The POC should check with the operator whether the requirements in the procedure were met. You are encouraged to ask for documentation which should all be posted in the FACET elog. (eg. a plot of the orbit, dispersion etc).
 
During the Shift
If the procedure changes during the course of the beam time, these deviations should be checked with FACET staff (FACET user manager, division director, science director etc.). This includes if tasks take longer than expected and the agreed upon length of the shift needs to be extended- this can usually be accommodated but will require discussion with facility staff.
 
This also includes tunnel access requests.
 
Maintain communications with your operator. Do not leave MCC without telling the operator where you are going and how to contact you.
 
The facet elog must be used. Please see the separate FAQ on the facet elog.
 
At the end of the shift
At the end of your beam time, the experimental team on shift must put in a summary. This really helps communication with the users, accelerator physicists and accelerator operators. We also use the reports from you to write the reports to DOE about how we are using beam time.
 
To generate a summary go to http://ad-ops.slac.stanford.edu/facet-shift-report/shift_summary_form/ and fill out the form.
When you are satisfied with you report, click on "SUBMIT" and the report will be saved in a database and also an entry will be made in the FACET e-log. Please go to the FACET e-log and make sure that the summary was added.


​What do I do on completion of my beamtime?

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After the Shift

Data analysis is expected after the data is collected and before the next data set is obtained. This requires use of calibrated in advance detectors and developing/testing data processing algorithms before run time. This is uniform requirement for all the experiments and excellent practice for science! Taking data blindly without understanding either its quality or its implications is unlikely to yield the best results. Subsequent beam time cannot be given without data analysis of previous beam time.
The procedure for the second shift will be expected after the completion of the first shift (should a second shift be necessary). As above, the procedure will be reviewed and passed to Jerry Yocky for scheduling.
 
(It is obviously advisable to have the second/third/fourth etc shift procedure prepared in advance and to revise it when lessons are learnt from beam time.)
 
It is likely that a meeting with Vitaly, Mark and Christine is needed to look at the analysis and plans for the next shift. It certainly makes it quicker to "review" if we meet face to face. If a meeting is not arranged, please contact us (just drop by offices or call cell phones).
 
 
8am the next day (or the next Monday for weekend beam time)
You are expected to send a representative to the 8am meeting in MCC. See here.
 
It is possible for facility staff to be the representative but you must make this arrangement in advance and provide adequate detail to them to report on the beamtime.


​How do I get more beam time?

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​For various reasons, you may need more beam time.

We build "float" into the FACET schedule such that we can accommodate requests for more beam time typically towards the end of the run.

In fact, you may find that you have been allocated less time than originally requested because we need to see early goals accomplished before scheduling the "stretch" goals.

If you anticipate needing and being awarded more beam time, please keep yourself available for the end of the run (discuss with the FACET staff).

When you have your early analyses complete, present the analyses and shift request (please produce a coarse outline) to your facility Point of Contact.



SLAC SLAC National Accelerator Laboratory, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy