targ_temp

Target temperature corrections 04/12/06

Some background material first:

Temperature sensor calibration: http://www.jlab.org/~gaskelld/XEMPT/cryotargets_summer04.html
Tables of density vs. temp for LH2 and LD2: LH2 LD2
Abbreviated tables: http://www.jlab.org/~smithg/target/Spring-03%20tgt/Slide45.JPG
Epics definitions: http://www.jlab.org/~smithg/target/SP03-epics.txt

Temperature sensor calibration:

Loop1
Ref_channel vs. ch1 and straight line fit, deviation from a straight line fit

Ref_channel vs. ch1 and straight line fit, deviation from a straight line fit

Loop2
Ref_channel vs. ch1 and straight line fit, deviation from a straight line fit
Ref_channel vs. ch1 and straight line fit, deviation from a straight line fit

Parameterizations Ref channel [K] = (1) + (2)*(sensor value [K] )
Loop1 ch1: 0.0801 0.85256
Loop1 ch2: -0.0825 0.81225
Loop2 ch1: 0.0026 0.9978
Loop2 ch2: 0.0217 0.9925

Uncertainties
Loop1, ch1 sigma+offset = 0.036 K
Loop1, ch2 sigma+offset = 0.054 K
Loop2, ch1 sigma+offset = 0.010 K
Loop2, ch2 sigma+offset = 0.013 K

Equation of state at Pressure = 24 psia (9.3 psig)

LH2 parameterization dens [g/cm3] = 0.08163+0.10309E-03*T-0.31262E-04*T**2
LD2 parameterization dens [g/cm3] = 0.1864+0.79270E-03*T-0.75279E-04*T**2

Eg
LH2 at 19.0 K, parameterization = 0.07230 g/cm^3
LD2 at 22.0 K, parameterization = 0.16740 g/cm^3
These values are within 0.02 %of the values given in the target training slide.

It turns out that for the July running period, it does not look like the loop temperatures were written to the data stream. So, I looked through all the target checklists and determined checked the loop temperatures

July '04 LH2 temp = 23.00 +- 0.02 K
July '04 LD2 temp = 22.00 +- 0.02 K

Dec '04 LH2 temp = 19.00 +- 0.02 K
Dec'04 LD2 temp = 22.00 +- 0.02 K

The July LH2 temperature was corrected using the calibration above for Loop 1 Channel 2 (Ref temp = -0.0825 + 0.81225*loop temp)

July '04 LH2 temp = 18.599 +- 0.02 K

Using the corrected temperature and the parameterization for the equation of state, The densities of the liquid targets were

July '04 LH2 dens = 0.07273 g/cm^3 +- 0.030%
July '04 LD2 dens = 0.16740 g/cm^3 +- 0.030%

Dec '04 LH2 dens = 0.07230 g/cm^3 +- 0.030 %
Dec'04 LD2 dens = 0.16740 g/cm^3 +- 0.030%

Using the inner diameter corrected for thermal contraction and beam x offset here

July '04 LH2 thickness = 0.2858 g/cm^2 +- 0.6%
July '04 LD2 thickness = 0.6587 g/cm^2 +- 0.6%

Dec '04 LH2 thickness = 0.2860 g/cm^2 +- 0.6 %
Dec'04 LD2 thickness = 0.6617 g/cm^2 +- 0.6%

NB, there is also a 0.6%uncertainty in the thickness due to boiling. The final thicknesses are

July '04 LH2 thickness = 0.2858 g/cm^2 +- 0.85%
July '04 LD2 thickness = 0.6587 g/cm^2 +- 0.85%

Dec '04 LH2 thickness = 0.2860 g/cm^2 +- 0.85 %
Dec'04 LD2 thickness = 0.6617 g/cm^2 +- 0.85%