(OPTICS) CALIBRATIONS, Spring 2003 ----------------------------------- version 2.0, 23/2/2003 General remarks. ---------------- F2: standard use of HMS; only normal elastic calibrations at some angles needed for determining the precise kinematics Baryons: HMS at momenta up to 5.1 GeV/c needs study of saturation effects on the needed excitation (99-118 suggests that they still are negligible up to 5.1 GeV/c) and on the optics (sieve slit runs needed) SOS at 1.6 GeV/c is definitely in the saturation regime; reliable (reproducable) way how to set the fields needed plus full optics study (sieve, Y, delta); check of offsets with 1H(e,e'p) ("heepcheck") at E'=1.6 GeV/c Fpi: HMS standard SOS needs check of optics at 0.8 GeV/c and full calibration at 1.74 GeV/c; because of limitations due to the lowest available beam energy the check will be done at 1.15 GeV/c, but the optics has been shown to be constant up to about 1.20 GeV/c; offsets to be checked with 1H(e,e'p) at both settings Remark about elastics (single) with HMS: The position of the elastic peak yields a(n angle dependent) relation between E, E' and theta, while the yield gives a check on our overall normalization; measuring at a range of angles costs hardly any time and gives us detailed information. Limitations: The minimum SOS angle is 18 degrees. At higher E_e the count rate for 1H(e,e'p) with e' in SOS gets rather small, since Q2 has to be large because E_e' must be below 1.76 GeV in SOS. (the luminosity of a 50 muA beam on a 4 cm LH2 target times a solid angle of 6.8 msr is 3*10^9 fm^-2.sr; the elastic cross sections in units fm^2/sr are listed as 'sigma' below). It is of no use to reverse the roles of SOS and HMS for heepcheck, since the polarity changes most probably introduce unwantedly large systematic uncertainties. The following point is extremely important: Centering of the beam --------------------- Before starting any calibration runs make sure that the beam is at the right position both horizontally and vertically. This remark applies at any new beam energy, but especially at the first one (during the same beam energy one may use the bpm's to keep the beam at the same position provided the required readings have been 'calibrated' by the method described below). For the vertical beam position it seems best to use the sieve-slit plot of X'-Y' (I use upper case for target quantities, lower case for fp quantities) from HMS. The central row should be at 0 within 1 mrad. For the horizontal position look at the plot of x vs. y and x vs. y' (so fp variables!). The central line should be vertical in both of them. If not, move the beam horizontally (0.5-1.0 mm should be sufficient unless the accelerator guys did a lousy job) till x vs. y looks fine. x vs. y' should be ok now, too. If not, call an expert (Rolf, Henk, ???). (Relevant plots to be specified). Then do a sieve-slit measurement and look at the X'-Y' plot and the histogram for Y. The central Y' column should be at 0, but Y may be off by 1 mm (this is a known inconsistency, which does not influence the physics). (Relevant plots to be specified). It is best to put the HMS for this procedure at an angle where we know that the 'pointing error' is approx. zero (angle to be specified). NB. Unfortunately there is not a similar method to check if the beam is centered now also for SOS. Some inconsistency in central X' and Y' between HMS and SOS have been observed. We will have to look into this when we take the HMS and subsequent SOS data. Specific calibration runs c.q. partial run plan. ------------------------------------------------ During commissioning and preparation of F2: 1.542 GeV beam Center the beam as described above. SOS delta scan at 1.15 GeV/c setting with H elastic put SOS at a central momentum of 1.15 GeV/c and keep it there, while changing the angle e-e th_e' e_e' delta sig 1542.0 60.0 846.5 -26.39 0.1055E-06 1542.0 58.0 869.9 -24.35 0.1293E-06 1542.0 56.0 894.2 -22.24 0.1601E-06 1542.0 54.0 919.3 -20.06 0.2002E-06 1542.0 52.0 945.1 -17.82 0.2531E-06 1542.0 50.0 971.6 -15.51 0.3236E-06 1542.0 48.0 998.9 -13.14 0.4188E-06 1542.0 46.0 1026.8 -10.72 0.5491E-06 1542.0 44.0 1055.3 -8.24 0.7297E-06 1542.0 42.0 1084.3 -5.71 0.9835E-06 1542.0 40.0 1113.8 -3.15 0.1346E-05 1542.0 38.0 1143.6 -0.56 0.1872E-05 1542.0 36.0 1173.6 2.06 0.2647E-05 1542.0 34.0 1203.8 4.68 0.3811E-05 1542.0 32.0 1233.9 7.29 0.5592E-05 1542.0 30.0 1263.8 9.89 0.8375E-05 1542.0 28.0 1293.2 12.45 0.1282E-04 1542.0 26.0 1322.1 14.97 0.2008E-04 1542.0 24.0 1350.2 17.41 0.3227E-04 1542.0 22.0 1377.2 19.76 0.5336E-04 1542.0 20.0 1403.0 22.00 0.9108E-04 1542.0 18.0 1427.2 24.10 0.1613E-03 at 38 degrees combine with heepcheck (HMS on + polarity) e_e th_e' e_e' q th_q Q2 sigma 1542.0 38.0 1143.6 952.0 47.7 0.75 0.1872E-05 During F2: 2.298 GeV beam NB. some SOS and HMS measurements may be done at the same time perhaps Center the beam carefully. SOS optics check with sieve and quintar at 1.15 GeV/c th_e' = 18 degrees SOS central momentum = 1.15 GeV/c collect at least 10^6 good counts (count rate to be calculated; probably large) NB. quintar with targets at z=0, +4, -4, +7.5, and -7.5 cm will give Y values at 18 degrees of 0, +1.25, -1.25, +2.33 and -2.33 cm. SOS delta scan at 1.60 GeV/c setting with H elastic put SOS at a central momentum of 1.600 GeV/c and keep it there, while changing the angle (angle order is not relevant; perhaps the best is to start with heepcheck and later repeat the central angle) heepcheck e-e th_e' e_e' q th_q Q2 sig 2298.0 34.7 1600.7 1339.6 42.9 1.31 0.4111E-06 scan e-e th_e' e_e' delta sig 2298.0 49.9 1227.8 -23.26 0.3421E-07 2298.0 48.4 1260.5 -21.22 0.4178E-07 2298.0 46.9 1294.1 -19.12 0.5147E-07 2298.0 45.5 1326.4 -17.10 0.6303E-07 2298.0 44.1 1359.5 -15.03 0.7784E-07 2298.0 42.7 1393.4 -12.91 0.9696E-07 2298.0 41.3 1428.1 -10.75 0.1219E-06 2298.0 39.9 1463.5 -8.53 0.1547E-06 2298.0 38.6 1497.0 -6.44 0.1948E-06 2298.0 37.3 1531.1 -4.31 0.2474E-06 2298.0 36.0 1565.7 -2.15 0.3174E-06 2298.0 34.7 1600.7 0.05 0.4111E-06 2298.0 33.4 1636.2 2.26 0.5381E-06 2298.0 32.1 1672.0 4.50 0.7122E-06 2298.0 30.8 1708.0 6.75 0.9533E-06 2298.0 29.5 1744.2 9.01 0.1291E-05 2298.0 28.2 1780.4 11.28 0.1771E-05 2298.0 26.9 1816.6 13.54 0.2462E-05 2298.0 25.6 1852.6 15.79 0.3470E-05 2298.0 24.3 1888.3 18.02 0.4961E-05 2298.0 22.9 1926.2 20.39 0.7417E-05 2298.0 21.6 1960.8 22.55 0.1096E-04 SOS delta scan at 1.74 GeV/c setting with H elastic put SOS at a central momentum of 1.740 GeV/c and keep it there, while changing the angle (angle order is not relevant; perhaps the best is to start with heepcheck and later repeat the central angle) heepcheck e-e th_e' e_e' q th_q Q2 sig 2298.0 29.6 1741.4 1163.7 47.7 1.04 0.1261E-05 scan e-e th_e' e_e' delta sig 2298.0 45.0 1338.1 -23.10 0.6790E-07 2298.0 43.6 1371.5 -21.18 0.8411E-07 2298.0 42.2 1405.7 -19.21 0.1051E-06 2298.0 40.8 1440.6 -17.21 0.1326E-06 2298.0 39.4 1476.3 -15.16 0.1688E-06 2298.0 38.0 1512.7 -13.07 0.2173E-06 2298.0 36.6 1549.6 -10.94 0.2826E-06 2298.0 35.2 1587.2 -8.78 0.3717E-06 2298.0 33.8 1625.2 -6.59 0.4948E-06 2298.0 32.4 1663.7 -4.39 0.6669E-06 2298.0 31.0 1702.5 -2.16 0.9108E-06 2298.0 29.6 1741.4 0.08 0.1261E-05 2298.0 28.2 1780.4 2.32 0.1771E-05 2298.0 26.8 1819.4 4.56 0.2527E-05 2298.0 25.4 1858.1 6.79 0.3662E-05 2298.0 24.0 1896.5 8.99 0.5399E-05 2298.0 22.5 1936.9 11.32 0.8348E-05 2298.0 21.0 1976.5 13.59 0.1319E-04 2298.0 19.5 2014.9 15.80 0.2135E-04 2298.0 18.0 2052.0 17.93 0.3543E-04 HMS elastic e-e th_e' e_e' sigma 2298.0 10.5 2207.5 0.7463E-03 2298.0 14.0 2142.2 0.1585E-03 2298.0 18.0 2052.0 0.3543E-04 2298.0 22.0 1950.2 0.9699E-05 2298.0 26.0 1841.5 0.3118E-05 2298.0 30.0 1730.3 0.1147E-05 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 2298.0 15.0 1000.0 do this measurement with the sieve slit in its normal position PLUS with the sieve slit shifted vertically by half a row 2298.0 15.0 600.0 2298.0 15.0 450.0 3.32 GeV beam Center the beam carefully. HMS elastic e-e th_e' e_e' sigma 3320.0 10.5 3134.3 0.2067E-03 3320.0 14.0 3004.2 0.3389E-04 3320.0 18.0 2829.9 0.5908E-05 3320.0 22.0 2639.9 0.1342E-05 3320.0 26.0 2444.6 0.3782E-06 3320.0 30.0 2252.3 0.1276E-06 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 3320.0 12.0 2000.0 do this measurement with the sieve slit in its normal position PLUS with the sieve slit shifted vertically by half a row 4.409 GeV beam Center the beam carefully. SOS optics check with sieve and quintar at 1.6 GeV/c th_e' = 18 degrees SOS central momentum = 1.60 GeV/c collect at least 10^6 good counts (count rate to be calculated; probably large) SOS optics check with sieve and quintar at 1.74 GeV/c th_e' = 18 degrees SOS central momentum = 1.76 GeV/c collect at least 10^6 good counts (count rate to be calculated; probably large) HMS elastic e-e th_e' e_e' sigma 4409.0 10.5 4087.4 0.6024E-04 4409.0 13.0 3935.1 0.1346E-04 4409.0 16.0 3730.0 0.2822E-05 4409.0 20.0 3435.5 0.4861E-06 4409.0 24.0 3135.3 0.1130E-06 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 4409.0 12.0 3000.0 do this measurement with the sieve slit in its normal position PLUS with the sieve slit shifted vertically by half a row 4409.0 12.0 2000.0 4409.0 12.0 1000.0 4409.0 12.0 600.0 4409.0 12.0 450.0 During Baryons 5.496 GeV beam Center the beam carefully. elastics in HMS e_e th_e' e_e' sigma 5496.0 12.0 4872.3 0.7057E-05 5496.0 15.0 4581.6 0.1194E-05 5496.0 18.0 4271.5 0.2658E-06 5496.0 21.0 3956.7 0.7393E-07 5496.0 24.0 3648.4 0.2468E-07 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 5496.0 12.0 4900.0 5496.0 12.0 4500.0 5496.0 12.0 4000.0 do this measurement with the sieve slit in its normal position PLUS with the sieve slit shifted vertically by half a row 5496.0 12.0 3000.0 SOS sieve check with thin (2mm?) C target e-e th_e' e_e' 5496.0 30.0 1600.0 check count rate! heepcheck at kinematics of experiment: e_e th_e' e_e' q th_q Q2 sigma 5496.0 55.0 1571.3 4771.6 15.6 7.37 0.7332E-10 count rate is rather small, but a check on the direction of q-vec, which is determined by SOS in the saturation region, seems essential; fortunately the high momentum setting of the actual experiment includes this kinematics (should be checked with a simulation; and is the resolution good enough?) During Fpi 5.248 GeV beam Center the beam carefully. elastics in HMS e_e th_e' e_e' sigma 5248.0 12.0 4676.4 0.9235E-05 5248.0 15.0 4407.9 0.1605E-05 5248.0 18.0 4120.1 0.3631E-06 5248.0 21.0 3826.5 0.1019E-06 5248.0 24.0 3537.5 0.3416E-07 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 5248.0 12.0 3400.0 SOS sieve check with thin (2mm?) C target e-e th_e' e_e' 5248.0 30.0 1750.0 heepcheck e_e th_e' e_e' q th_q Q2 sigma 5248.0 50.0 1750.5 4335.4 18.0 6.56 0.1725E-09 low count rates; 3 hr should give 5000 events 4.702 GeV beam Center the beam carefully. elastics in HMS e_e th_e' e_e' sigma 4702.0 12.0 4237.9 0.1704E-04 4702.0 15.0 4016.2 0.3164E-05 4702.0 18.0 3775.9 0.7469E-06 4702.0 21.0 3527.8 0.2150E-06 4702.0 24.0 3280.7 0.7307E-07 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 4702.0 12.0 3000.0 do this measurement with the sieve slit in its normal position PLUS with the sieve slit shifted vertically by half a row SOS sieve check with thin (2mm?) C target e-e th_e' e_e' 4702.0 30.0 1760.0 heepcheck e_e th_e' e_e' q th_q Q2 sigma 4702.0 48.0 1769.0 3755.9 20.5 5.50 0.4576E-09 low count rates; 2 hr should give 10000 events 4.210 GeV beam Center the beam carefully. elastics in HMS e_e th_e' e_e' sigma 4210.0 12.0 3834.1 0.3032E-04 4210.0 16.0 3586.6 0.3709E-05 4210.0 20.0 3313.4 0.6534E-06 4210.0 24.0 3033.3 0.1537E-06 4210.0 28.0 2760.3 0.4559E-07 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 4210.0 12.0 3400.0 SOS sieve check with thin (2mm?) C target e-e th_e' e_e' 4210.0 30.0 800.0 heepcheck e_e th_e' e_e' q th_q Q2 sigma 4210.0 51.0 1580.8 3441.9 20.9 4.93 0.6486E-09 th_e' is what we will use for Fpi, but e_e' is far off; nevertheless useful for angle offset check and out-of-plane 3.772 GeV beam Center the beam carefully. elastics in HMS e_e th_e' e_e' sigma 3772.0 12.0 3467.4 0.5170E-04 3772.0 16.0 3263.7 0.6923E-05 3772.0 20.0 3036.0 0.1291E-05 3772.0 25.0 2740.0 0.2283E-06 3772.0 30.0 2451.6 0.5571E-07 HMS sieve check with thin (2mm?) C target e-e th_e' e_e' 3772.0 12.0 3000.0 SOS sieve check with thin (2mm?) C target e-e th_e' e_e' 3772.0 30.0 800.0 heepcheck e_e th_e' e_e' q th_q Q2 sigma 3772.0 44.0 1772.3 2784.1 26.2 3.75 0.3459E-08 th_e' is what we will use for Fpi, but e_e' is far off; nevertheless useful for angle offset check and out-of-plane