A comparison of the target gauges for the February, March 2000 runs and December 1999.
In December 1999 we had a low enough electron energy, 845 MeV, to normalize the target density to the
Otterman and Amroun elastic cross sections on 3He. Then going to 4033 MeV we used the same target density obtained
from 845 MeV because the gauges reading pressure(haSC200_6_Sensor_2_R) and temperature (haITC502_5_Sensor_2_R)
read the same values. The density we determined from Dimitri's graph in December was 0.053 g/cm3. In March 2000
we ran at a higher gas pressure (154 psi compared to about 109 psi). The density from the gauges were 0.067 g/cm3,
again from DJM's graph, and the density by comparison to Otterman's cross sections at 644 MeV was 0.070 to 0.071 g/cm3. Thus the
combination of Dimitri's graph and the gauges gave densities that were low by no more than 5%.
In February 2000 we measured elastic scattering at Q2 = 5 at 1956 MeV with a pressure in the target of 114 psi. The
parallel kinematic data were measured with a pressure of 153 psi (at least for run 2422). This is close to the
condition in March so the density for run 2422 should be 0.070 g/cm3. An additional check on the validity of the
gauges as a measure of density can be found in the analysis of the Q2 = 5 elastic scattering points. In that
anaysis we deduced the cross sections at Q2=5 for various kinematic conditions. For most of the conditions we could
obtain the target densities from the Otterman cross sections at Q2 << 5. However, at 1956 MeV in February 2000
we could only get to Q2=5. Here using the gauges to get the density we obtained agreement to within about 3% to 4%
for all the Q2 = 5 points. The conclusion is that the gauges are a reliable way to obtain the densities if Dimitri's
equation of state graph from 4He is used and apprpriately scaled.
See http://www.calstatela.edu/academic/nuclear_physics/89044/comparison_q2_5.htm
February 2000, Q2 = 5 elastic |
February 2000,
kin18, Ee = 4.803 GeV run 2422 |
haL1_Fan_frequency_R : 67.5 |
haL1_Fan_frequency_R : 70.5 |
December, 1999,Ee = 845, Q2 = 5, density from Otterman |
December 1999, 4.033 GeV, Kin 16 |
March 2000, 0.644 GeV elastic, Q2=1.29 |