HRS Sieve and Collimator Offsets
(This is old dated Material)For new results see:
sieves_2000.htmStandard sieve offsets as reported by the survey group in September 1997 (DT#359).
Table 1 shows offsets of slit from the ideal position as defined by the dipole.Table 1
Offsets from Dipole axis |
(mm) |
|
Electron |
D x |
D y |
Sieve |
-0.4 |
4.1 |
Large Collimator |
-1.8 |
4.2 |
Hadron |
D x |
D y |
Sieve |
0.8 |
0.2 |
Large Collimator |
2.4 |
-0.1 |
Measurements of Q1's relative to the dipole axis from August 1996 and March 1999 (DT#508,283).
Table 2 shows amount of motion needed to put the magnets in the "correct" position.
Table 2
Fiducial |
DZ |
D X |
D Y |
D Z |
D X |
D Y |
DDZ |
DDX |
DDY |
3/12/99 |
8/16/96 (#283) |
||||||||
EQ1G |
9.49 |
0.81 |
-2.33 |
9.45 |
0.55 |
-2.28 |
-0.04 |
-0.26 |
0.05 |
EQ1J |
9.24 |
0.44 |
-1.24 |
9.28 |
-0.06 |
-1.11 |
0.04 |
-0.5 |
0.13 |
EQ1K |
10.11 |
0.76 |
-1.44 |
10.15 |
0.12 |
-1.27 |
0.04 |
-0.64 |
0.17 |
average |
9.61 |
0.67 |
-1.67 |
9.63 |
0.20 |
-1.55 |
0.01 |
-0.47 |
0.12 |
s |
0.4 |
0.2 |
0.6 |
0.5 |
0.3 |
0.6 |
0.0 |
0.2 |
0.1 |
3/19/99 |
4/23/97 |
(#352) |
|||||||
HQ1A |
1.07 |
-0.53 |
0.43 |
-0.03 |
-1.02 |
0.34 |
-1.1 |
-0.49 |
-0.09 |
HQ1C |
0.9 |
-0.23 |
-0.38 |
-0.1 |
-0.52 |
-0.63 |
-1 |
-0.29 |
-0.25 |
HQ1D |
0.31 |
-0.32 |
-0.21 |
-0.92 |
-0.45 |
-0.63 |
-1.23 |
-0.13 |
-0.42 |
HQ1M |
0.21 |
-0.46 |
0.19 |
-1.08 |
-0.98 |
0.09 |
-1.29 |
-0.52 |
-0.1 |
average |
0.47 |
-0.34 |
-0.13 |
-0.70 |
-0.65 |
-0.39 |
-1.17 |
-0.31 |
-0.26 |
s |
0.4 |
0.1 |
0.3 |
0.5 |
0.3 |
0.4 |
0.2 |
0.2 |
0.2 |
Measurements of the sieve relative to Q1 from 4/2/99. (DT#509).
Table 3 shows the results of measurements of the amount the collimator must be moved to put it at its "correct" position.Table 3
|
DX (mm) |
DY (mm) |
Electron |
|
|
Sieve |
0.17 |
0.44 |
Large Collimator |
Not measured |
0.16 |
Hadron |
|
|
Sieve |
-0.39 |
1.19 |
Large Collimator |
Not measured |
1.23 |
Summary:
In table 4 the results of combining tables 2 and 3 (DX and DY 99 and 96) are compared with the results reported in table 1 (DX and DY 97)
Table 4
Electron |
DX 99 |
DX 96 |
DX 97 |
DY 99 |
DY 96 |
DY 97 |
sieve |
0.84 |
0.37 |
0.4 |
-1.23 |
-1.11 |
-4.1 |
Large collimator |
1.8 |
-1.51 |
-1.39 |
-4.2 |
||
Hadron |
||||||
sieve |
-0.73 |
-1.04 |
-0.8 |
1.06 |
0.80 |
-0.2 |
Large collimator |
-2.4 |
1.10 |
0.84 |
0.1 |
Discussion:
The DX values are consistent at the sub-millimeter level for all three measurements on both arms. The DY97 values in the electron arm are almost 3 mm different from the 99 and 96 values, which agree at the sub-millimeter level. This discrepancy for DY on the electron arm is troubling. Since the measurements of the quadrupoles relative to the dipoles agree for 1999 and 1996 it is probably safe to assume that they are correct. One is left to speculate whether the 1997 measurements (Table 1 DT#359) or the 1999 measurements (Table 3 DT#509) are in error.
Recommendations:
Table 5: Offsets of sieves from the spectrometer axis (1999 measurements). Positive
D X means the sieve is shifted to the left. Positive D Y means the sieve is shifted up.
|
D X (mm) |
D Y (mm) |
Electron Sieve |
-0.84 |
1.23 |
Hadron Sieve |
0.73 |
-1.06 |
-JJL 6/29/99