I took a look at the kaon yield in the HEUB.
Define 'beam' as (s0.5)*(s2)*(s3)*(/s1a)*(/s1b)
'pi' as (bm)*(c2)*(c3)
'pi1' as (bm)*(c2)*(c3)*c1)
'heavy' as (bm)*(/c2)*(/c3)
'K' as (bm)*(/c2)*(/c3)*(c1)
The hardware for these defintions was set up in the fast trailer
independent of the normal trigger logic.
The counter c1 was pumped down to vacuum and the slowly filled with freon-12
in small steps of pressure. At each step the four rates above were taken.
The threshold for 18 GeV particles in F-12 is:
pi threshold = -97 kPa (-100 kPa = vacuum, 0 kPa = 1 atmosphere)
K threshold = -65 kPa
Pressure curves of pi1/pi and K/heavy were plotted as a function of pressure.
In the ideal case, the pi curve should show a sharp knee at approximately
-97 kPa, and the K curve at -65 kPa.
To see the pi curve click here
To see the K curve click here
The pi curve looks about as one would expect.
We do see a knee in the K pressure curve at the correct pressure -- but
the K content of the beam is much lower than the value reported in the
folk tradition of the mps.
The ratio of heavy/pi which contains K, pbar, cerenkov inefficiencies and
junk, is approximately 0.385%. The K/pi ratio must be less than this. We
measure K/pi about 0.3%.
Hugh Brown of the ags department has given us an estimate of the k content
of the beam based on Sanford-Wang fits to measured data. The assumptions
are: proton momnetum = 24.0 GeV/c
Kminus momentum = 18.0 GeV/c
production at 0 degrees.
The K/pi ratio at production is 0.54%, but our beam line - to the
cerenkovs - is 113 meters. Approximately 43% of the K's survive, yielding
an expected K/pi ratio of 0.24% -- in rough agreement with the measurement.
High voltage plateau curves for c1 -- click here
and c2 -- click here
and c3 -- click here
were made. The new high voltage settings are:
c1 3000 V
c2 2500 V
c3 3000 V
//end file