Re: [smclayto: pions in the beam?]

[Peter Kammel <kammel@one.npl.uiuc.edu>]

Dear Steve,

Interesting suggestion. Luis Alvarez discovered
Muon-Catalyzed-Fusion in 1956, in the Berkeley
bubble chamber (the pdm->mu+He3) reaction.
Actually in 1947 it was theoretically considered
to explain the pion-muon decay, just discovered.
---------------------------------
Hypothetical alternative energy sources for the "second meson" events
Frank, F.C. Source: Nature, v 160, 18 Oct. 1947, p 525-527
Country of publication: UK

Abstract: The following alternatives to the suggestion of Lattes et al
[Abstr. 1948A00417] for the generation of 4 MeV at the end of a meson
track are considered, and rejected, bearing in mind the chemical
constitution of the photo emulsion: induced - or K capture
processes; induced emission of single nucleons; induced -emission; induced
fission; processes with change of charge of 2, by conversion of neg. to
pos. meson; induced decay of naturally persisting nuclear
isomers. Processes involving the addition of a proton to some other
nucleus are discussed at length; these might take place through the
intermediate formation of a "mesonic hydrogen atom" by the meson entering
a hydrogen-like orbit round a proton. It is concluded that the latter
process, though possibly operative in nuclear reactions, is not
responsible for the observations of Lattes et al, and their explanation
remains the only feasible one.
--------------------------------

So the muon from pion decay is rather similar to the "Alvarez" muon.
However, negative pions will probably annihilate with the proton
before being captured. For pi+ there should be some events from decay
in flight (although with very limited efficiency).

Best regards

Peter


On Sat, 14 Jan 2006, Steven Clayton wrote:

> Correction: the decay muon would have ~60 MeV/c
> momentum, and we wouldn't see it in the TPC without
> higher voltage.
> 
> ----- Forwarded message from smclayto -----
> 
> To: Peter Kammel <kammel>
> Subject: pions in the beam?
> 
> Dear Peter,
> 
> is it possible to have pion contamination in our
> beam at the target position?  Because if there
> were any, they could look like the tracks I showed
> you the other day: incoming track (pion), with a
> transverse track (muon).  Then that muon would
> tend to have the energy to escape the fiducial
> volume and decay on a wall.  Just a thought, and
> maybe a naive one.
> 
> Steven
> 
> 
> ----- End forwarded message -----
> 

Peter Kammel  /  pkammel@uiuc.edu
Department of Physics, Loomis Laboratory
University of Illinois at Urbana-Champaign
1110 West Green Street, Urbana, IL 61801 
Tel (217) 333-5424 / Fax (217) 333-1215