The Muonic Hydrogen Lamb Shift Experiment at PSI
Abstract
A measurement of the 2S Lamb shift in muonic hydrogen (μ-p) is being prepared at the Paul Scherrer Institute (PSI). The goal of the experiment is to measure the energy difference ΔE(25 P 3/2-23 S 1/2) by laser spectroscopy (λ≈6μm) to a precision of 30 ppm and to deduce the root mean square (rms) proton charge radius with 10-3 relative accuracy, 20 times more precise than presently known. An important prerequisite to this experiment is the availability of long-lived μp2S -atoms. A 2S-lifetime of ∼1 μs sufficiently long to perform the laser experiment at H2 gas pressures of 1 2 hPa was deduced from recent measurements of the collisional 2S-quenching rate. A new low-energy negative muon beam yields an order of magnitude more muon stops in a small low-density gas volume than a conventional cloud muon beam. A stack of ultra-thin carbon foils is the key element of a fast detector for keV-muons. The development of a 2 keV X-ray detector and a 3-stage laser system providing 0.5 mJ laser pulses at 6 μm is on the way.
- Publication:
-
Hyperfine Interactions
- Pub Date:
- December 2001
- DOI:
- 10.1023/A:1020886314237
- Bibcode:
- 2001HyInt.138...55K