[BLAST_ANAWARE] target polarization - some food for thought

From: Hauke Kolster (hauke@lns.mit.edu)
Date: Sun Apr 25 2004 - 00:51:48 EDT


Tancredi,
I did calculations for the injected polarization of the deuterium
target and compared the results to the numbers that you showed
during the analysis meeting. I found an interesting result: The
polarization values that you showed are consistent with high
efficiencies and an unpolarized fraction of the target of 25%
if the polarization values are expressed as P_1 and P_2 in
Arenh"ovel's notation, which are related to commonly used target
polarizations P_z and P_zz as P_1=sqrt(3/2)*P_z and
P_zz=sqrt(1/2)*P_zz. That means measured polarizations P_1=0.75
and P-2=0.49 would result in target polarizations of P_z=0.64
and P_zz=0.68.

The attached figure shows the occupation numbers for hyperfine
states in injected states V+ (top left), V- (top right), and
T- (botom left). The last picture (bottom right) shows a plot
of vector (P_1) vs. tensor (P2) polarization for the ABS
calculations (solid boxes, dashed line) and experiemental data
(your results in open boxes with error bars and dotted lines).
Here I assumed no difference in P_2 for the vector states V+ and
V- and P_1=0 for the T- state.

I think that it is very unlikely that the good agreement between
the two data sets is just a coincidence, but it is no proof either.
Is it clear that the calculations of the theoretical asymmetries
and cross sections are carried out correctly? If one had switched
between the two systems at some point in the code, one would
produce the observed discrepancy between the vector and tensor
polarization.

Hauke

Details:
In my calculations I accounted for the transmission probabilities
of individual states through the ABS sextupole system, efficiencies
of the rf-transitions, and unpolarized contributions.
Tranmission probabilities:
\sigma_ff : states focused in first and second magnet system
\sigma_fr : states focused in first and rejected in second magnet system
\sigma_rf : states rejected in first and focused in second magnet system
\sigma_rr : states rejected in first and second magnet system




On Friday, April 23, 2004, at 05:51 PM, Tancredi Botto wrote:

>
> _ Overall succesfull meeting focussed on eep/ed data from D2 run (3/24
> - 4/3)
> _ montecarlo effects important.
> _ Comparison to recon data fair. Needs study of kin corrections
> _ Extracted polarization values seem consistent
> Pz : 75 +- 4 Pzz : 49 +- 9 (from eep )
> _ Pzz : 51 +- 4 (from T20 )
>



This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:30 EST