Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charged particle spectra from $\mu^{-}$ capture on Al   Published data on the emission of charged particles following nuclear muon
capture are extremely limited. In addition to its interest as a probe of the
nuclear response, these data are important for the design of some current
searches for lepton flavor violation. This work presents momentum spectra of
protons and deuterons following $\mu^{-}$ capture in aluminum. It is the first
measurement of a muon capture process performed with a tracking spectrometer. A
precision of better than 10% over the momentum range of 100--190 MeV/c for
protons is obtained; for deuterons of 145--250 MeV/c the precision is better
than 20%. The observed partial yield of protons with emission momenta above 80
MeV/c (kinetic energy 3.4 MeV) is
$0.0322\pm0.0007(\text{stat})\pm0.0022(\text{syst})$ per capture, and for
deuterons above 130 MeV/c (4.5 MeV) it is
$0.0122\pm0.0009(\text{stat})\pm0.0006(\text{syst})$. Extrapolating to total
yields gives $0.045\pm0.001(\text{stat})\pm0.003(\text{syst}) \pm
0.001(\text{extrapolation})$ per capture for protons and
$0.018\pm0.001(\text{stat})\pm0.001(\text{syst})\pm
0.002(\text{extrapolation})$ for deuterons, which are the most precise
measurements of these quantities to date.

37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th