General Users at the APS and LS-CAT
LS-CAT provides beamtime to general users through
the APS General User
Program. This time is available free of charge* through a
competitive proposal process. Allocations are made three times a year. Is
your need urgent? Rapid Access time is also available free of charge*.
Just submit a normal APS General User Proposal with Rapid Access
APS General User time, including Rapid Access beamtime requests, are
available to both academic and industrial users.
Proposals with Rapid Access Requests
This process takes much less time to arrange than the normal process:
- Find a facility that has time around when you need it.
(here to see LS-CAT
available slots.) Save yourself some grief and call and/or email the
person in charge of scheduling and see if there is a slot available
for rapid access.
- Submit a normal proposal (see below) but with a Rapid Access
Beamtime Request. You'll find this in the "Beamtime Request" tab of
the proposal: click on the "For which scheduling period are you
applying?" drop down box. Chose the period marked "(RAPID ACCESS
- On the "Choice Of Beamline" line be sure the beamline you
contacted in the first step is listed FIRST. They will not be able to
schedule your time otherwise.
- Your proposal will still be reviewed and in times of high demand
you may lose out if someone else wants the same slot and has a
proposal with a better rating. However, you do not have to wait for
the Proposal Review Panel or the Beamtime Allocation Committee to meet
before your time can be assigned.
Proposals with Normal Beamtime Requests
The calendar for APS General User Proposals can be
You can refer to this table for the following explanation of the
- You submit a proposal by the "Proposal Deadline" date. Part of
the proposal is the Beamtime Request. During the 2 years your
proposal is valid you may make many beamtime requests, up to a maximum
number of 8 hour shifts assigned by the Proposal Review Panel (see the
next step). Here are some pointers:
- Be sure to request enough time to cover your needs for 2 years.
Be realistic: the reviewers know what it takes to collect data at the
APS and understand the complexity of the project you propose to work
- Do not request MAD data collection at a fixed wavelength station.
It wont work but it will cause a 1 to 2 week delay while the BAC tries
to figure you what you want.
- The APS uses units of 8 hours shifts: 3 shifts per day.
- Beamlines (including LS-CAT) schedule beamtime in units of days.
That is, you should request time in multiples of 3 shifts. Note that
some facilities require that you schedule a minimum of 6 shifts (2
days). LS-CAT allows General Users to schedule time in blocks of 1 day.
- A "day" at the APS can range anywhere from 14 hours to 25 hours
depending on the details of the schedule. Be sure to ask if this is
important to you.
- The beamtime request section of the General User Proposal has a
place to indicate when you cannot accept beamtime. Please take the
time to fill this out. If you do not want to come to the APS during
your homecoming game, put it down. Although there is no guarantee
your blackout date can be honored, you will be expected to accept
(without complaint) any date that is not listed.
- The Proposal Review Panel (PRP on the calendar) meets and assigns
a score for the proposal: 1 is best (and very rare) while 5 has the
lowest priority. While the scoring system is not perfect, it does a
reasonable job of ranking most proposals. The biggest mistake people
make that leads to poor scores is the omission of details in the
- The Beamtime Allocation Committee (labeled BAC on the calendar)
meets and assigns the proposal to a particular beamline. This is
where you can expect problems if you requested time at a station that
cannot accommodate your experiment.
- The facility where you have been assigned will contact you to
schedule your time.
*The APS charges proprietary usage fees when applicable.