Reduction of coherent betatron oscillations in a muon g - 2 storage ring experiment using RF fields

Authors

On Kim, Institute for Basic Science, Daejeon
On Kim, Korea Advanced Institute of Science & Technology
Meghna Bhattacharya, University of Mississippi
Seungpyo Chang, Institute for Basic Science, Daejeon
Seungpyo Chang, Korea Advanced Institute of Science & Technology
Jihoon Choi, Institute for Basic Science, Daejeon
Jihoon Choi, Korea Astronomy and Space Science Institute
Jason D. Crnkovic, Brookhaven National Laboratory
Sudeshna Ganguly, University of Illinois Urbana-Champaign
Selcuk Hacömeroǧlu, Institute for Basic Science, Daejeon
Manolis Kargiantoulakis, Fermi National Accelerator Laboratory
Young Im Kim, Institute for Basic Science, Daejeon
Young Im Kim, Korea University
Soohyung Lee, Institute for Basic Science, Daejeon
William M. Morse, Brookhaven National Laboratory
Hogan Nguyen, Fermi National Accelerator Laboratory
Yuri F. Orlov, Cornell University
B. Lee Roberts, Boston University
Yannis K. Semertzidis, Institute for Basic Science, Daejeon

Document Type

Article

Publication Date

6-1-2020

Abstract

© 2020 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft. This work demonstrates that two systematic errors, coherent betatron oscillations (CBO) and muon losses, can be reduced through application of radio frequency (RF) electric fields, which ultimately increases the sensitivity of the muon g - 2 experiments. As the ensemble of polarized muons goes around a weak focusing storage ring, their spin precesses, and when they decay through the weak interaction, μ+ → e+ νeν-μ, the decay positrons are detected by electromagnetic calorimeters. In addition to the expected exponential decay in the positron time spectrum, the weak decay asymmetry causes a modulation in the number of positrons in a selected energy range at the difference frequency between the spin and cyclotron frequencies, ω a. This frequency is directly proportional to the magnetic anomaly a μ = (g - 2)/2, where g is the g-factor of the muon, which is slightly greater than 2. The detector acceptance depends on the radial position of the muon decay, so the CBO of the muon bunch following injection into the storage ring modulate the measured muon signal with the frequency ω CBO. In addition, the muon populations at the edge of the beam hit the walls of the vacuum chamber before decaying, which also affects the signal. Thus, reduction of CBO and unwanted muon loss increases the a μ measurement sensitivity. Numerical and experimental studies with RF electric fields yield more than a magnitude reduction of the CBO, with muon losses comparable to the conventional method.

Relational Format

journal article

Recommended Citation

Kim, O., Bhattacharya, M., Chang, S., Choi, J., Crnkovic, J. D., Ganguly, S., Hacĭömeroğlu, S., Kargiantoulakis, M., Kim, Y.-I., Lee, S., Morse, W. M., Nguyen, H., Orlov, Y. F., Roberts, B. L., Semertzidis, Y. K., Tishchenko, V., Tran, N. H., & Yucel, E. B. (2020). Reduction of coherent betatron oscillations in a muon g − 2 storage ring experiment using RF fields. New Journal of Physics, 22(6), 063002. https://doi.org/10.1088/1367-2630/ab83d0