CHRNS: Event mode software

Overview

With the improvements in hardware, sample environment, and new data packets/storage of events we require new software for the production, distribution, caching, saving, histograming, reducing, fitting, monitoring, and feedback to users/NICE. 

• CHRNS Computing resources are available via ORCiD login within NIST
• DAVE and Mslice for MACS
• SASView for VSANS
• Refl1D for CANDOR
• Developing necessary web-based tools to perform all other tasks

New rebinning API and web interface for event mode data

Built around the newest data management tools from the CHRNS-FAIR initiative, we have designed a web interface that allows inspection and rebinning (<1 second!) of time-stammped neutron data. The API allows for automated data binning. The code is located here.

Refl1D/CANDOR data fitting

• Enabled remote (web-based) access to a 'live' fitting server for interactive fitting sessions, or static fit results for batch fits for the Refl1D analysis software, which is used for analysis of data from the CHRNS CANDOR instrument.

• The interface is detachable and re-attachable to the fitting session at any time
• Parameter error bars are determined with MCMC, correlations, fit history etc. visually represented
• Necessary for Autonomous Experiments
• Low-code fitting development: 
  • Simple web app lets users build physical models
  • Compare model to data directly in-app
  • Code is generated from the visual model representation and piped to Refl1D

Experimental optimization of the neutron instrument, measurement, and sample to greatly reduce measurement times and increase data quality. 

• Remote Execution of CANDOR experimental optimizations 
• Jupyter Notebook data fitting using Refl1D
• Feature-complete experimental optimization for bio-materials
  • C++ classes wrapped in Python for speed and compatibility
  • Declarative model langue for use in Refl1D
• See section on CANDOR Fluids handling robot for 1) ‘immediate’ feedback to the user on the information content in a measurement 2) a mechanism for feeding results from these routines back into the NICE control software to be used in intelligent, automated determinations of how to efficiently complete the measurements.

SASView/VSANS data fitting and modeling

• decoupled GUI from backend computations 
• GPU/CPU multiprocessor support for fitting
• SasView: https://github.com/SasView/sasview
• SasModels: https://github.com/SasView/sasmodels

Intelligent experiment-design and experiment-planning tools using predictions of information content based on user-supplied models (bio/soft materials initially) 

• Web-based Application : https://charlotte.ncnr.nist.gov/jupyter)
• Remote Execution of SANS experimental optimizations 
• Feature-complete experimental optimization 
  • lipid vesicle molecular model
  • Any SASView model
  • Monte Carlo Markov Chain fitting of SANS data
  • Instrument resolution 
  • We have implemented Autonomous Reflectivity measurements on CANDOR, and once we gain experience and user feedback through hot-testing, we will use that understanding to provide intelligent, automated determinations of how to efficiently complete VSANS measurements. The ‘immediate’ feedback to the user on the information content of a measurement and statistical error analysis for a given model(s) can be used to reduce overcounting in SANS. This does not require a time-resolved experiment to leverage the capability.

DAVE and Mslice

Used for reducing MACS data and has been adapted to visualize time-slice data, taking special care of the error bar due to low count rate of the event mode. (DAVE)