MUCOOL Meeting Notes, May 7

  News:

Al moretti says that modulator construction has started in Lab G
and the drawings of the magnet and cryostat being assembled at LBL
by Mike Green are here.  Evidently the drawings imply safety
requirements for the pressure vessel are going require some 
effort. Al Moretti has new keys for Lab G.

  Paul:

In one slide Paul outlined an argument that Dave Carey made about
chromatic effects in plasma and Lithium lenses being half 
as bad as in solenoids and quads.  The reason being that the current
causes the field that directly focuses, rather than focusing being
a more indirect result of the fields.  In any case quad systems with
large apertures and small beta*'s are very tough to build.

Wishi is trying to put bent solenoids in COSY.

  Valery:

Valery and Nikolai have put out a note on a bunched beam line designed
around a quadrupole channel, with some space for rf cavities.  The 
average beta is about 2 m for quad spacings of about 1 m and 15 cm.
The line is presumed to be at 0 degrees to the proton beam, and is
assumed to capture 500 MeV/c +- huge dp, pion momenta,

A 90 degree FODO with waists provides some room for cavities.  The
quads are grouped in pairs, but the average beta is still roughly
two times the complete cell length, and there is 1 m of space for
linacs in every cell. 

The acceptance of the channel goes like R^4, and the mu/pi ratio
goes like R so the number of Muons goes like R^5.  Cavities should be
large also, and since the decay to the muon introduces more perpendicular
momentum than anything but a very thick window, it should be possible to 
use thin al or cu foils between the sections of the rf cavity
without degranding the beam.  Collision lengths are relatively long
and collisions don't contribute, to first order.

Valery and Nikolai presented monte carlo results showing the pion and 
muon distributions after the capture and decay section showing the
dependence on R and momentum.

(busybody note from J.N.: The proposed beam, with large momentum and 
angular acceptance, located at zero degrees in the lab, might have many
high energy protons and other particles which would make experiments
difficult.   In general, beamlines use both momentum analysis
with bending magnets, and some other method of separation to produce
reasonably pure beams.  High energy protons have enormous kenetic
energy and produce meny secondaries.  Better to be away from zero degrees.)

  Norbert:

He presented a plan for the initial bunched beam cooling line to 
be in a tunnel parallel to the BOONE target enclosure.  This muon line
would be essentially an underground linac facility, supported by
a klystron gallery on the surface.

  William:

Leeson presented initial thoughts on the filtering the pions out of
a muon beam.  He would use perhaps 2 m of absorber which would
intercept and scatter pions preferentially.

  Vincent and Derun:

Both measurements of Q and resonant frequencies as a function of 
temperature and calculations of an rf coupler for a pillbox cavity were
presented.  

At room temperature measurements of Q were about half of the theoretical
predictions.  At low temp the Q increases but less then expected.  The
resonant frequencies were about as predicted.  As the temperature is
lowered, the Q varies discontinuously, presumeably due to the way
the copper cavity is contracting.  The discontinuities seem to be 
due to the motion in the joints, and the anomalously small Q seems
also due to effects relating to the joints.

The feeling was that reassembling the cavity with would improve 
things.  This will be underway soon.

The coupler design is being done with MAFIA, using an algorithm that 
involves 1) finding the resonant frequency, 2) studying power flow on 
resonance and 3) adjusting the dimensions of the coupler until one
obtains critical coupling.  This is underway but not done.