Experimental evidence of production of directional muons from a laser-wakefield accelerator

Abstract

We report on experimental evidence of the generation of directional muons from a laser-wakefield accelerator driven by a PW-class laser. The muons were generated following the interaction of a GeV-scale high-charge electron beam with a 2cm-thick Pb target and were detected using a Timepix3 detector placed behind a suitable shielding configuration. Data analysis indicates a $(99.1\pm0.5)$% confidence of muon detection over noise, in excellent agreement with numerical modelling. Extrapolation of the experimental setup to higher electron energies and charges suggests the potential to guide and separate from noise approximately $10^4$ muons/s onto cm$^2$-scale areas for applications using a 10 Hz PW laser. These results demonstrate the possibility of generating and transporting directional muon beams using high-power lasers and establish a foundation for the systematic application of laser-driven high-energy muon beams.

Figures (7)

• Figure 1: a. Sketch of the experimental setup. b. Examples of angularly resolved electron spectra measured before the insertion of the converter target. Colorbar is in arbitrary units. c. Angularly integrated spectrum averaged over 10 consecutive shots without converter. The solid blue line indicates the average and the grey shading the standard deviation.
• Figure 2: a. Simulated spectrum of $\mu^-$ (orange) and $\mu^+$ (blue) generated during the interaction of an electron beam as depicted in Fig. \ref{['Fig1']} with a 2cm-thick lead converter. b. Distribution of parent particles for $\mu^-$ (blue) and $\mu^+$ (orange) reaching the detector. Trid. indicates direct electroproduction (trident), while BH denotes Bethe-Heitler pair production initiated by a bremsstrahlung photon in the converter.
• Figure 3: Side-view of the simulated distribution through the experimental setup of all muons (a), muons generated by pion decay (b), positrons (c), photons (d), electrons (e), and all pions (f) through the experimental setup. The position of the detector is highlighted in frame (a) and all colorbars are in units of particle per primary electron per cm$^2$.
• Figure 4: Simulated distribution of track length (a), mean energy deposited (b), and standard deviation within the track (c) from FLUKA simulations for $300\pm50$ MeV muons (blue) and electrons with a flat energy distribution extending up to 10 MeV (green) interacting with the TimePix3 detector (simulation details in the article). The simulated data points have been fitted with a rational function of the form: $y(x) = (p_1 x + p_2)/(x^2 + q_1 x + q_2)$.
• Figure 5: a) TimePix3 raw data accumulated over 10 consecutive shots with a 2 cm Pb converter. b) TimePix3 data from (a) filtered with a 2ns temporal window around the expected muon arrival time (details in the article). c) TimePix3 data from (b) with the additional filter of track straightness. d) TimePix3 data from (c) with only 1 pixel-wide tracks.