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FACET FAQs

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SCHEDULING

​SCHEDULING FAQS

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​What is the current shift schedule?

Answer Collapse/Expand Text:

 Here. 



​How many shifts will my experiment get?

Answer Collapse/Expand Text:

This is usually arranged in advance of publishing the schedule through communication with the FACET user manager. She will request and digest your beam requests and work with you to develop a reasonable number of shifts to fulfil science goals.

If your results during a run indicate a need for further shifts, a detailed proposal on how many shifts, the goals and the analysis of shifts so far should be produced. This should be sent to the FACET User Manager who will pass it on for review by the FACET Division.

Many experiments at FACET get single shifts sporadically across a run (gaps between shifts can allow for data analyses and are usually part of a user beam request). Long programmatic studies can expect to get a series of shifts across a week or two for example. The assignment of shifts usually comes down to the science need and also the recommendations of the SAREC committee for priorities for the FACET facility.



​Why are you asking for shift plans and procedures?

Answer Collapse/Expand Text:

The total number of experimental shifts is relatively low at FACET. Efficient planning for experimental time is therefore required for the experiment to be successful.

The facility needs to be provided with a detailed, step-by-step plan for your beam time so we can be certain that the planning has been completed. This also means that we can plan better on our end to provide good beam and support.



​Can we be guaranteed good beam?

Answer Collapse/Expand Text:

At FACET we focus on good quality beam delivery.

The beam will be fuly characterised and tuned before being delivered to experiments.

This may result in a delay to delivering beam to the experiment if more work is needed to get good beam. Your patience when your shift does not start exactly on time is appreciated!



​How long is a shift?

Answer Collapse/Expand Text:

​In order to deliver good quality beam, FACET spends a lot of machine time to daily maintenance activities and machine development. We therefore do not schedule experiments around the clock (maximum shift length is usually 12 hours).

Shifts are of flexible duration according to the science needs. Users must have a written procedure for their work that clearly indicates the time that is needed. That procedure will be agreed upon with FACET staff and then executed. If the 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.


What do I need to do to get my beam time approved? (What is the timeline for what is due to be submitted when?)

Answer Collapse/Expand Text:

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 (see "how do I write a good procedure" in the FAQ).

 

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).

 

Two weeks before scheduled beam time

The procedure for your beam time studies 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. Note that there may not be much time between shifts so having a prepared draft procedure for

 

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.

 

 

Day of beam time

Jerry Yocky or designee instructs the accelerator operators on shift on how to set up the beam and check out the hardware as requested in the procedure.

 

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 (and sometimes the accelerator physicist) 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 and physicist 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.

 

 

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.

 



​How do I write a good beam time procedure?

Answer Collapse/Expand Text:
We're learning as we go at FACET but it's clear that a good beam time procedure helps the operators know what to deliver and helps the experimenters to focus on achieving results. The more experience we gain at running, the more we understand what constitutes a good procedure. So you can expect the "answer" to this to change as we learn.
 
 
 
All procedures need to be headed with the expected date and time of the beam time.
  
The procedure needs to be sent to Vitaly, Mark and Christine. The procedure will be reviewed and discussed with the experimenters if necessary (and it is usually necessary!). If approved, the procedure will be forwarded by Vitaly or a designee to Jerry Yocky who instructs the operators on how to prepare the beam.
 
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, 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.
 
Examples:


​What happens if I don't have an approved procedure for my shift?

Answer Collapse/Expand Text:

Beam time, even parasitic work, won't go ahead without a written procedure that has been approved by FACET management. This includes things like software tests with beam and controlling items remotely.



Why can't I do something that I have done before?​

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Just because you've done it before, doesn't mean it's okay to do it again. Each procedure is evaluated for that particular period of beam time. So if you want to do something that was in an earlier procedure and it was approved back then, unless it was approved in your current procedure, don't do it.

Conditions may have changed or lessons learnt. So please don't assume it is allowed unless explicitly okayed!



​What if I need to do something not on the procedure?

Answer Collapse/Expand Text:

We understand that plans do change.

Changes to beam time procedures should be directed to Vitaly (call him night or day) or his designee who can evaluate the impact and approve or not.
 
If a change happens during beam time, initiate the call.
 
If you ask operations to do something outside of the procedure, they should call us too but they may not so please don't hesitate to involve us to communicate with ops to confirm changes to procedure.


​Will I get beam time during the day or during the night?

Answer Collapse/Expand Text:

Summary:

FACET User shifts of beam typically begin between 2pm and 7pm and run for up to 12 hours. Multiple experiments may be scheduled for the same shift, running in series.

Detailed Daily Schedule:

Around 8/9am each morning, beam physicists and accelerator operators set up the beam or engage in machine development studies to support delivery to users.

Beam is usually ready for delivery in the afternoon. 4pm is a typical start time. Some experiments that require the best stability won't begin until 7pm.

Preferably, all experiments scheduled for this block/shift are done by 4am and the accelerator operators perform standard maintenance and activities that improve the beam delivery for the next day.

At the latest, experiments should end by 7am which is when stability starts to be poor. Ending later also impacts the ability of the accelerator operators to set up for the next day.

The exact number of hours that an experiment gets is pre-arranged. Experiments are requested to keep to their time-slots so as to not affect other FACET users. Any changes, for example beam time extensions, need to be approved by FACET management.

 

 

See the image below.

 

WeeklySchedule.jpg



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