Information on precautionary site access restrictions to Fermilab's Batavia site in response to coronavirus/COVID-19
We continue to review all events currently planned for the next sixty days and organizers will be notified if their event must be canceled, postponed, or held remotely. Please, check back on Indico during this time for updates regarding your meeting specifics.
As DOE O 142.3A, Unclassified Foreign Visits and Assignments Program (FVA) applies not only to physical access to DOE sites, technologies, and equipment, but also information, all remote events hosted by Fermilab must comply with FVA requirements. This includes participant registration and agenda review. Please contact Melissa Ormond, FVA Manager, with any questions.

indico search will be reestablished in the next version upgrade of the software: https://getindico.io/roadmap/
For public events you may use either https://library.fnal.gov/indico-search/ or your browser's search engine: "your search string" site:indico.fnal.gov

18-19 June 2018
Fermilab, Wilson Hall
US/Central timezone

Magnetic Field Status of the Muon g-2 Experiment

Jun 19, 2018, 10:15 AM
15m
One West (Fermilab, Wilson Hall)

One West

Fermilab, Wilson Hall

Oral Presentation Muon Physics

Speaker

Rachel Osofsky (University of Washington)

Description

The muon g-2 experiment at Fermilab (E989) aims to measure the anomalous magnetic moment of the muon $a_\mathrm{\mu}$ to a precision of 140 parts per billion (ppb). This new measurement will shed light on the 3.5 sigma deviation between Standard Model calculations and the previous measurement (E821) at Brookhaven National Laboratory, and will test Standard Model extensions. The muon g-2 experiment measures the difference between the cyclotron and spin precession frequencies of muons in a highly uniform magnetic field, where the magnetic field over a muon's trajectory must be known to 70 ppb. The magnetic field in the muon storage region is mapped by a trolley carrying a circular array of 17 nuclear magnetic resonance (NMR) probes, but because the trolley can not be present while muons are being stored, the magnetic field drift is tracked using a suite of 378 NMR probes embedded in the top and bottom of the vacuum chambers. The trolley NMR probes use a petroleum jelly sample and, in order to measure the field absolutely, must be calibrated against a water filled probe with very well understood characteristics. The calibration process is underway to calibrate all 17 trolley probes to a 30 ppb precision, with the inner ring of trolley probes now calibrated. The other important step in achieving the desired precision is making the magnetic field in the storage region as homogeneous as possible. The last passive step in achieving the required field homogeneity was the adjustment and installation of over 10,000 iron shims in and around the muon storage region. Higher order multipole moments of the magnetic field distribution across the storage region are controlled using 100 concentric coils located above and below the vacuum chambers. The current distribution in these so called surface coils is adjusted to reduce magnetic field variations across the storage region to less than 2 parts per million. An overview of the magnetic field hardware, calibration, and shimming status will be presented.

Primary author

Rachel Osofsky (University of Washington)

Presentation Materials