Notes Gep at 12 GeV
--------------------

Focus on either HMS, SHMS or MAD to detect proton
and have FPP in tandem with the Bigcal to detect electron.


Important considerations:
1. Need FPP
2. High proton momentum
3. Understand spin matrix


FPP
----

HMS has advantage of having an FPP. 
The FPP could be moved to SHMS. I assume that it
could also be moved to MAD. Maybe Ron can check on
this?

For 12GeV the analyzer power used in estimate is
from an  extrapolation of previous Dubna data. 
The efficiency is assumed to be 50%.
The limit to the Q2 is mainly from how far one wants
to push the extrapolation of Ay and the count rate.


Kinematics
-----------


First scenario:

Q$^2$ = 12 GeV$^2$

Beam energy = 8.8 GeV
Proton mom = 7.27 angle=13.3
Electron mom = 2.4  angle=44.23
 Jacobian dsig_e/dsig_p = 9

Beam energy = 11 GeV
Proton mom = 7.27 angle=17.4
Electron mom = 4.6 angle=28.17
 Jacobian dsig_e/dsig_p = 1.5


HMS, SHMS and MAD can accept the
momentum. 

2nd scenario:

Q$^2$ = 14 GeV$^2$

Beam energy = 11 GeV
Proton mom = 8.34 angle=14.04
Electron mom = 3.54  angle=34.89
 Jacobian dsig_e/dsig_p = 4.35


SHMS and MAD can accept the
central momentum. 



Spin Matrix
------------

HMS is the simplest to understand and will be tested
by previous experiment.

By hand-waving arguments one can argue that SHMS
will be easier to understand than MAD. But both
will be difficult compared to HMS.

Ask Lubomir Pentchev to help to come up with more
quantitative arguments.

Rates and errors
----------------

used 20cm target for SHMS and MAD
used 15cm target for HMS.

Spec  Bend Angle
---- -----------
HMS      25
SHMS     18.5
MAD      32

Spec Ebeam Qsq   I(uA)  xn(cm^2/sr) sol_ang  Rate   time    Ac    eff
                                              /sec   hr
---  ----- ---   ----   ----------- ------   -----  ----   ----- ------
HMS   8.8   12.   75.   0.11349E-36 .0060     2.56  1440.0 0.0549 .5000
HMS   11.   12.   75.   0.44389E-36 .0060     2.78  1440.0 0.0549 .5000
SHMS  11.   12.   75.   0.44389E-36 .0045     2.09  1440.0 0.0549 .5000
MAD   11.   12.   75.   0.44389E-36 .0150     6.96  1440.0 0.0549 .5000
SHMS  11.   14.   75.   0.10488E-36 .0045     1.08  2880.0 0.0478 .5000
MAD   11.   14.   75.   0.10488E-36 .0090     2.16  2880.0 0.0478 .5000



Spec Ebeam Qsq     h     chi    err (Ge/Gm)
---- ----- ------ ---- -----    ----------
HMS   8.8  12.000 0.80 350.28   0.1071
HMS   11.  12.000 0.80 350.28   0.1100
MAD   11.  12.000 0.80 448.36   0.0587
SHMS  11.  12.000 0.80 259.21   0.1071
MAD   11.  14.000 0.80 513.53   0.0895
SHMS  11.  14.000 0.80 296.88   0.1245



Personal Comments
------------------

I would propose Q2 = 12 GeV as the example kinematics. Now that
I look at things, Q2 = 14 is too close. The Q2 = 12 will cover
a large Q2 range almost to Q2 = 14 . The rates at Q2 = 15 are half
those at 14.