Dear SNS/HFIR User Community,
 
After careful consideration, we have decided to accept proposals only for the Spallation Neutron Source (SNS) for our fall proposal call closing at noon, September 18, 2019. 
 
The High Flux Isotope Reactor (HFIR) is scheduled to resume operation in November 2019.  The HFIR operating period from November 2019 - April 2020 will be used for instrument commissioning and for running the previously approved user experiments that were impacted by the shutdown.  Many HFIR instruments underwent extensive upgrades, and more days than originally anticipated will be needed for both carryover experiments and commissioning time. HFIR will be ready to run new user experiments by May 2020.
 
The spring proposal call will close on February 26, 2020.  This call will be for experiments anticipated to run at HFIR between May-December 2020, and at the SNS between July-December 2020.
 
We recognize that this is a change in what we originally advertised to the community, and we apologize. By not including HFIR in this call and adding two months to the spring proposal call, we will be able to accept a full allocation of new proposals and will have completed all the experiments that were impacted due to the HFIR shutdown.
 
HFIR Instrument Upgrades During Shutdown
 
HFIR will return to operations with extensive improvements to many of the instruments.  The improvements range from new collimators to data acquisition systems to detectors.  The instrument teams provided the following summaries of the improvements on their respective instruments. 
 
HB-1 (P-TAX):A development project has been underway to develop a spherical neutron polarimetry capability for HFIR.  Such a capability has not been available to the U.S. neutron scattering community and will enable quantitative understanding of complex magnetic structures such as non-collinear antiferromagnets and incommensurate and chiral magnetic structures.  A prototype device has been constructed based on the novel application of high-Tc superconducting films to provide a zero-field environment at the sample position.  The high intensity polarized beams of neutrons on HB-1 are required to test and commission this device, a necessary step towards making this capability available to the user community.
 
HB-1A (FIE-TAX):HB-1A has undergone a complete replacement and upgrade of the incident beam monochromator assembly.  This instrument utilizes a double bounce PG (002) monochromator system.  Both monochromators have been replaced together with the shield containing the second monochromator.  This upgrade has enabled optimization of the vertical focus on the instrument which should result in a factor of three increase in flux on sample.
 
HB-2A (Powder): Several improvements have been implemented on HB-2A.  During the previous cycle, sample environment upgrades included several successful experiments and publications using the He4 cryostat 3-sample changer (temperature range 1.5 – 300 K).  This allows three samples to be loaded and easily switched in seconds during your experiment.  During the shutdown, this same capability has been implemented in our Janis CCR (4 – 300 K) and will be fully commissioned in the coming cycles.  Development work is underway to extend sample changer capabilities to ultra-low temperatures for a new “push-button” ³He (0.3 – 300 K) system.  We have also increased the highest field capability to 8 T with successful offline tests of the magnet compatibility on the instrument.  An offline automatic sample can sealer is also being developed, with the option of a standard atmosphere as well as over-atmosphere of He exchange gas for ultra-low temperature measurements.  This autosealer, which will be available in early 2020, will both save time and mitigate leaks by offering a reproducible standardized sealing method.  Polarization measurements are continuing to expand with further experiments in the coming cycles.  These incident beam (half-polarized) measurements allow extreme sensitivity to under 0.1 muB for materials with a net moment (ferromagnets and ferrimagnets).  To further improve the background for low signal magnetic scattering, tests will be performed to incorporate an argon chamber before the detectors.  Additionally, a new beam stop set-up will be tested to allow measurements to lower Q with lower background. Finally, looking to HB-2A’s future, in the coming year we will be testing a prototype for a new detector design that will improve count rates and offer new capabilities such as in situstudies.
 
 
HB-2B (NSRF2): The strain scanning diffractometer located at the HB-2B beam port has been dramatically upgraded.  The upgrade consisted of the installation of a new 30cm x 30cm Denex ³He position-sensitive detector to replace the array of seven linear detectors which were previously utilized on the beam line.  This represents an increase in active detector area from 70 cm² to 900cm­².  This increase in detector size will result in a greater instrument throughput (estimated factor of three times) due to the larger out of plane detector coverage.  Additionally, the 2θ field of view will be increased from ~4° to ~18° field of view with the new detector.  This will allow for simultaneous measurement of multiple peaks in materials of interest to the engineering community.  This multi-peak measurement will allow for faster and more complex mapping of multi-phase and composite material systems.  With the new detector, an entirely new diffracted and incident optics package is now integrated into the instrument.  This upgraded package will allow for the continued use of slits to map gauge volume dimensions of less than 1 mm for small samples.  For larger samples, a 3D printed radial collimator system is available, to allow for a greater stand-off distance from the gauge volume to detector while maintaining good signal to noise and precise mapping of desired gauge volumes.  The first set of new collimators are 2 mm and additional collimators will be fabricated to enable a range of gauge volumes.  The incident slit assembly is automated such that their position and size can be controlled on the fly during a mapping script.  Additionally, the data acquisition system (DAS) has migrated to EPICS controls like the SNS BL-7, VULCAN, instrument for consistency across instruments for the user base.  The NSRF2 version, however, has a specific focus on additional mapping capabilities.  The new DAS will allow for the mapping of samples in the user-defined sample coordinate system while utilizing an easy to understand interface for mapping.  Data will immediately be available to users on the analysis cluster and reduction of data will be automated.  Users will be able to view, plot, fit, and export their measured data using a new python-based program, PyRS, which can be accessed remotely on the analysis cluster from anywhere.
 
HB-2C (WAND²): WAND² has upgraded its DAS electronics using the modular ADC-ROC to feed in any analog signal as metadata into the data stream.  With this set-up and event filtering, stroboscopic measurements are now possible.  The frozen monochromator focus axis has been repaired and can now be changed to improve vertical divergence.  For experiments requiring a controlled humid atmosphere between 0 and 80 C a new humidity chamber has been designed. Two “dry” 3He CCRs have been purchased and will be commissioned in the upcoming cycles These systems expand the temperature range for standard experiments down to 300mK (and up to 300K). 
 
HB-3A (Four-Circle): HB-3A was recently upgraded with a new large 2D area detector, which makes it capable of measuring single crystal neutron diffraction under extreme sample environment including temperature (0.05-800 K), magnetic field (0- 5 T),  electric field (0-10000 V/cm), and pressure up to 10 GPa.  Half-polarized neutron diffraction is also available with the wavelength of 2.54 Å and we will continue this development toward its full capability for the general user community. 
 
CG-1D (IMAGING):In collaboration with Louisiana State University, CG-1D is implementing a new capability called the Talbot-Lau grating interferometry.  The beam line will be equipped with three Gd-based gratings (G0: source, G1: phase, and G2: analyzer) capable of detecting features between ~ 500 nm and a few mm.  This technique is effectively measuring a small-angle neutron scattering signal on pixel sizes of ~ 40 μm in three dimensions.  The beam line’s servers have recently been upgraded and testing of the EPICS interface is ongoing.  Future upgrades include a re-design of the detector translation stage to allow all three detectors (CCD, Microchannel Plate (MCP) and sCMOS) to be aligned with the beam remotely, allowing rapid changes between detectors.  A compact furnace, which is aimed to accommodate high temperature (up to 1400 °C) measurements in air, has been procured.  The control hardware has been designed and EPICS integration will start in the next few weeks.  In addition, updates have been released to the online neutron imaging signal simulation tool, Neutron Imaging Toolbox (NEUIT).  Major updates include input validator, error feedback, and the ability to export/upload complex sample input.
 
CG-2 (GP-SANS) and CG-3 (Bio-SANS): The small-angle neutron scattering (SANS) instruments at HFIR are undergoing major construction work that will entirely replace the movable guide/collimator section.  This improvement includes more robustly designed vacuum vessels and translation stages that operate in-vacuum, which avoids issues previously encountered with collimator motor-shaft vacuum feed-throughs.  In addition, the new vacuum vessels are larger and the new design provides added space that can be used for future additions of neutron optical components such as focusing optics or polarizers.  The improvement project further includes new, non-magnetic neutron guides, suitable for polarized neutron studies.  In addition, GP-SANS and Bio-SANS are receiving new instrument control and data acquisition software (DAS), based on the EPICS platform, which is the current standard at SNS and some HFIR instruments.  The new EPICS software will incorporate features that users like about interacting with the HFIR SANS, such as the user friendly table-scan option at Bio-SANS, and it will lead to a common look and feel of the instrument control user interface at all SANS instruments at the SNS and HFIR (EQ-SANS, GP-SANS, and Bio-SANS).  This will make data acquisition even easier for users who use both SNS and HFIR SANS for their experiments.  The new data acquisition software supports neutron detection in event mode, which provides added capability for advanced time-resolved studies.  In addition, new unified data reduction software is being developed.  The new software will be web-based.
 
CG-4D (IMAGINE):The instrument has a new sample mounting capability that utilizes a kappa-goniometer that, when commissioned in early 2020, will allow users to collect complete data with fewer settings compared to the standard phi-only goniometer from crystals mounted in loops.  A new sample alignment set-up has been designed and built.  It will allow crystal centering on top of the instrument using a video camera and will be installed on IMAGINE in 2020.

 
Sincerely,

Neutron Sciences User Office
Oak Ridge National Laboratory
neutronusers@ornl.gov
(865)574-4600