Analysis of |B| variation during January 2024 nn' experiment at GP-SANS instrument, ORNL

1. Description
   1.1 Background
   1.2 GP-SANS Analysis Scripts
2. Usage
3. Author(s) and Acknowledgement
4. References

This repository contains scripts that are

The figure above shows the simulated probability of neutron regeneration (color scale) as a function of possible $\delta m$ and mixing angle $\theta_0$ in the SNS 2020 nn' experiment [1] for a 4.7 T Magnetic Field. The January 2024 nn' experiment at HFIR aims to continue this search, varying |B| to hopefully observe a different countrate, as this may suggest the existence of mirror matter [2].

Analysis of our experiment involves looking at the GP-SANS detector countrate within different Regions of Interest, and comparing those countrates across runs with different |B|. If a positive effect is observed for a particular |B|>0 vs |B|=0, this will be evidence for the possible existence of mirror matter.

Although the scripts in this repo are specific to the January 2024 mirror matter search at the GP-SANS beamline, an effort has been made to make them as generally applicable as possible. Capabilities include: Run selection using criteria referenced in ONCAT summary, countrate within defined ROI analysis for preprocessed data files.

1. Gather MNO files or McStas summaries of MNO files, store in <data_dir>/MNO_files/. Make sure to also have DetIDmap.csv and ONCAT_summary_HFIR_CG2_IPTS-<ipts>.csv in <data_dir>
2. Edit settings.py to specify relative paths (such as <data_dir>), and choose run selection criteria
3. Run analyze_B_runs.py, and view output. On first run, MNO files will be analyzed which may take some time, but subsequent evaluations will be faster.

James M. Rogers, University of Tennessee - Knoxville
contact: [email protected]

This research used resources at the High Flux Isotope Reactor, a DoE Office of Science User Facility operated by the Oak Ridge National Laboratory.

[1] Gonzalez, Francisco M., Cary Rock, Leah J. Broussard, Lisa DeBeer-Schmitt, Matthew J. Frost, Lawrence Heilbronn, Erik B. Iverson, et al. “Improved Limits on n \rightarrow n’ Transformation from the Spallation Neutron Source,” 2024.
[2] Z. Berezhiani, P. Ciarcelluti, D. Comelli, and F. L. Villante, International Journal of Modern Physics D 14, 107(2005), arXiv:0312605 [astro-ph].

Under the GNU AFFERO GENERAL PUBLIC LICENSE

Currently in progress as of 04-29-2024