HySpec Remote Experiment Restrictions

O. Garlea, M. Graves-Brook, B. Winn

At HYSPEC most of our sample exchange is performed manually. The startup day for a single crystal experiment is typically dedicated tofor sample installation and, alignment and instrument/background optimization. During this time one of the HYSPEC instrument staff is generally onsite, although we may return to offices or home during sample cooling. We expect to interact with you via SLACK during this, showing you photographs of the sample and interacting via video, to confirm that you are OK with how we are mounting. We also expect you to be ready with for providing your sample’s lattice dimensions information,and desired orientation and known strong nuclear Bragg reflections, which simplifies sample alignment with monochromatic beam. (photo with SE mounting something…) In the unlikely event that your experiment includes multiple sample environments (for example .. ?) or even less likely event that an environment fails and needs immediate replacement, in person presence by sample environment staff will also be required. (photo with optic rail components, cadmium manual shielding, beam stops and manual apertures) During startup we may also change the configuration of HYSPEC manually. This may include adding or removing optic rail components between drum shield and sample, reconfiguring background-reducing cadmium shielding or incident beam attenuators, or trying out different manual aperture settings. Note that a These activities generally occur on the first day of an experiment when the sample is being mounted, but a significant configuration change, like rotating the detector vessel, may require in-person adjustment of some of these the shielding components. (photo with photographs of refill and possibly ULT pump and leak checking) Some of our sample environments require periodic in-person attention, usually for refilling cryogens, but also for the transition to ultra-cold temperatures for some of our inserts and back out, which requires pumping configuration changes and leak checks. Although Instrument Hall Coordinators have also been trained to support some of these activities, because they are shared between multiple instruments and facilities, scheduling their support can be uncertain and we prefer to plan ahead using instrument and sample environment people instead. Our goal in planning with you your experiment is to schedule these whenever possible during week-day business hours, and for this we may benefit from a three-way chat between the user group, instrument team, and sample environment support staff; such meetings will be coordinated by the HYSPEC instrument team. This planning ensures that the best possible measurements are obtained in a timely fashion during your available beamtime, and that staff are alert and focused when performing activities onsite. (photo with photographs of new environments) Our sample environment suite is in a state of constant development and upgrade, and especially with newer or upgraded environments the change of sample conditions may require in-person attention, either due to manual activities or as an at-the-ready monitoring situation. In these cases, we also prefer to schedule sample condition changes in advance, and prefer week-day work-hours for rapid response if further attention is required . (photo with floor space and possible motion, sample environment spaghetti and the swinging arm) Changing incident energy is either an instrument team remote operation or an in-person operation. Unlike other direct geometry spectrometers at the SNS, HYSPEC employs a vertical focusing Bragg array which requires the sample and sample environment to move when changing incident energies. When moving the sample environment to satisfy different Bragg conditions, we have three key concerns.
(video-?- of motion of drum shield) -First, the detector vessel moves with the sample and can touch walls, the equipment lift, ladders, carts and support equipment for sample environment. There are safety systems in place, but we prefer to monitor those conditions especially when first setting up, and when triggered the safety systems require in-person mitigation for further motion (we usually like to back a way just a bit). Because of this condition, the instrument team also exclusively controls the detector vessel rotation, even when setting up table or script scans. -Second, the support lines between sample environment and its support equipment often restrict the range of motion of the sample environment itself, so that the support equipment may need to be repositioned as we change incident energy. This condition motivates you as an experiment team to consider in advance what the range of preferred incident energies might be, so that we can try out a range of incident energies to evaluate whether the support equipment has a ‘sweet spot’. -Third, the change from “low energy configuration” (below 6.5 meV ) to high energies (above 7.5 meV ) and back requires in-person activities to close or open our ‘swinging arm’, which is integral to the shielding about our focusing arrays. When closed it covers a large opening in our drum shield for higher incident energies. When open it permits access to lower incident energies and that large opening is then hidden behind other stationary shielding. (a few more optic rail shots and the elevator video of we can swing it) The next condition concerns a transition from unpolarized to polarized modes of operation and back, and is an exclusive concern for experiments requesting some form of polarization analysis as part of their experiment. First, certain optics and systems may require manual setup, such as the flipper, guide fields and 3D coils surrounding the sample environment. Second, whenever we change between the polarizing supermirror array and the radial collimator, this is an in-person manual operation, in part to ensure safe translation of the elevator, and in part due to quirks of the pneumatic system which require additional training and the installation or removal of manual jacks underneath the radial collimator. (shot of our IPPS system and one finger…) Finally, we have configured our control system to require in-person presence for either opening or closing our secondary or tertiary shutters, and to obtain access to the experiment or beam permit. This activity may be performed by HYSPEC instrument staff or by instrument hall coordinators.