3 research outputs found
Laser excitation of the 1s-hyperfine transition in muonic hydrogen
The CREMA collaboration is pursuing a measurement of the ground-state
hyperfine splitting (HFS) in muonic hydrogen (p) with 1 ppm accuracy by
means of pulsed laser spectroscopy to determine the two-photon-exchange
contribution with relative accuracy. In the proposed
experiment, the p atom undergoes a laser excitation from the singlet
hyperfine state to the triplet hyperfine state, {then} is quenched back to the
singlet state by an inelastic collision with a H molecule. The resulting
increase of kinetic energy after the collisional deexcitation is used as a
signature of a successful laser transition between hyperfine states. In this
paper, we calculate the combined probability that a p atom initially in
the singlet hyperfine state undergoes a laser excitation to the triplet state
followed by a collisional-induced deexcitation back to the singlet state. This
combined probability has been computed using the optical Bloch equations
including the inelastic and elastic collisions. Omitting the decoherence
effects caused by {the laser bandwidth and }collisions would overestimate the
transition probability by more than a factor of two in the experimental
conditions. Moreover, we also account for Doppler effects and provide the
matrix element, the saturation fluence, the elastic and inelastic collision
rates for the singlet and triplet states, and the resonance linewidth. This
calculation thus quantifies one of the key unknowns of the HFS experiment,
leading to a precise definition of the requirements for the laser system and to
an optimization of the hydrogen gas target where p is formed and the laser
spectroscopy will occur.Comment: 21 pages, 4 figure
Diffusion of muonic hydrogen in hydrogen gas and the measurement of the 1 hyperfine splitting of muonic hydrogen
The CREMA collaboration is pursuing a measurement of the ground-state hyperfine splitting (HFS) in muonic hydrogen (p) with 1 ppm accuracy by means of pulsed laser spectroscopy. In the proposed experiment, the p atom is excited by a laser pulse from the singlet to the triplet hyperfine sub-levels, and is quenched back to the singlet state by an inelastic collision with a H molecule. The resulting increase of kinetic energy after this cycle modifies the p atom diffusion in the hydrogen gas and the arrival time of the p atoms at the target walls. This laser-induced modification of the arrival times is used to expose the atomic transition. In this paper we present the simulation of the p diffusion in the H gas which is at the core of the experimental scheme. These simulations have been implemented with the Geant4 framework by introducing various low-energy processes including the motion of the H molecules, i.e. the effects related with the hydrogen target temperature. The simulations have been used to optimize the hydrogen target parameters (pressure, temperatures and thickness) and to estimate signal and background rates. These rates allow to estimate the maximum time needed to find the resonance and the statistical accuracy of the spectroscopy experiment