sieve-offsetsnew

HRS Sieve and Collimator Offsets (This is old dated Material)

For new results see:sieves_2000.htm

Standard 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	Dx	Dy
Sieve	-0.4	4.1
Large Collimator	-1.8	4.2
Hadron	Dx	Dy
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 Q₁from 4/2/99. (DT#509). Table 3 shows the results of measurements of the amount the collimatormust 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:

Recheck the measurements of the sieve relative to the quadrupoles and, if possible, look into the records of the 1997 (DT#359) measurements for verification. Another possibility is to directly measure the position of the sieves relative to the dipoles.

For the present use the results of the 1999 measurements, all other things being equal, they are the most recent and hence the most relevant to recent measurements.

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

Privacy and Security Notice