Weekly Meetings
- Meetings will be held on Thursdays 11:30-12:30 in F228.
- Next meeting May 12th.
- Join by Bluejeans by phone and computer +1.888.240.2560 (US Toll Free) Enter Meeting ID: 653182486
Notes from April 21st meeting
- Rolf and Tanja presented a beta version of the commissioning plan.
- Need to contact John Arrington to see if he has an old detector checkout plan.
- For carbon elastic, need to know if the front cerenkov can be replaced by a vacuum pipe and what is the time for the change out.
- Next meeting present plots of sieve for different steps in Q1, Q2 and Q3 to determine how to do the determination of the SHMS magnet settings.
- For beam pipe, need to determine what minimum SHMS angles the experiments need in first 2-3 years.
- Look at HMS quads data to determine what cycling procedure is needed in future.
Preparation plans
- Magnets.
- Determination of B versus I curve. Develop new code for setting SHMS. Revise HMS field setting codes.
- Cycling procedure especially for HB. Look what is done for the HMS.
- Double check that the magnet field between magnets are superpositions.
- Survey of the positioning of magnets.
- Carbon elastics at 2 pass.
- Survey of collimators, detectors and beamline components.
- Survey of HMS/SHMS pointing at different angles. Look into what was done in the past for HMS commissioning. Determine a list of angles for survey.
- Need to come up with the sieve pattern as a function of quad settings.
- Need to look at use of ideal dipole versus TOSCA field map for HB in COSY.
- Checked with Howard about the quad field centering. The idea that Howard had didn't work. Need to rely on mapping data.
- Integration of detector checkout and optics.
Carbon elastics
- Results from Dipangkar for 1 pass- 2.2 GeV, and 2 pass -4.4 GeV). Measurements at 8-9.5 are doable.
- Using the 2nd plan configuration of the initial beam pipe ( SHMS to about 10, HMS to 10.5) it was checked by Dan Young that SHMS could go to 9 degrees drawing of beam pipe region.
- Beam energies available for Fall 2016 and all of 2017.
| Pass |
Beam Energy (MeV)
|
| 1 |
2217
|
| 2 |
4317
|
| 3 |
6417
|
| 4 |
8517
|
| 5 |
10617
|
| 5.5 |
11667
|
SHMS HB
Sensitivity of scattering angle to HB central field setting
- The distance, d1, from the targe center to the magnetic entrance of the HB is 138.4cm.
- The effective length, d2, of the HB is nominally 75cm. This is presently used in COSY . Need to update using mapping data.
- The distance, d3, from the magnetic exit of the HB to he sieve is 40cm.
- The horizontal angle and position relative to the central ray are y and yp. Delta = 100*(p-pcentral)/pcentral .
- At HB magentic entrance, yp_ent=yp_tar and y_ent(cm) =y_tar(cm) + d1*yp_tar(radians)
- For the HB, the transport of yp and y only depends on delta and delta^2 terms.
- yp_exit (mr) = -0.52*delta + 0.0052*delta^2 + yp_ent(mr)
- y_exit (cm) = -0.019*delta + 0.00019*delta^2 + (d1+d2)*yp_tar(radians) + y_tar(cm)
- y_sieve (cm) = y_exit + d3*yp_exit(radians)
- To make it through y_sieve = 0 with y_tar = 0
- y_exit = -d3*(-0.52*delta + 0.0052*delta^2 + yp_tar(mr))
- (d1+d2+d3)*yp_tar(mr) = (0.019+0.52*d3)*delta - (0.00019+0.0052*d3)*delta^2
- yp_tar (mr) = 0.153*delta - 0.00153*delta^2 .
- So delta = 6.5% gives yp_tar = 1 mr.
Mapping
- A Lakeshore Hall probe was used for the mapping measurements. The probe has a linearity error as a function of magnetic field which was measured by the company ( Table of data). This linearity error is different for positive and negative field directions. In the data table, the Error = abs(Measured Field)-abs(True Field). So for positive fields True Field = Measured Field - Error. For negative fields True Field = Measured filed + Error.
- Document and plots about mapping of B versus I at center of HB bore and the fringe fields in the beam region.
- Measurements of B at bore center versus I when ramping magnet from 0 to +3900 and back to 0. Then switch polarity and ramp from 0 to -3900 and back to zero.
- plot of absolute difference between B when ramping magnet up and down versus I when going to +3900 and -3900.
- plot of relative difference between B when ramping magnet up and down versus I when going to +3900 and -3900.
- Plot of difference in B between ramping up to +3900 and ramping up to -3900 versus current.
- When ramping to negative currents there was a trip at I= -3139A. Plot of difference between first ramp to -3139A and the second.
- Document and plots about mapping Of B versus z for five different x,y locations (center,top,bottomleft and right) for I = 2000, 3000, 3500 and 3900A.
- Presentation on the harmonic analysis of the HB using field measurements at radius of 5.9cm at center of magnet at currents of -1200,-2000,-3000,-3500,-3900 and +3900.
- Table of momentum versus current:
| Momentum (GeV) |
Current (A)
|
| 3.687 |
1200
|
| 6.110 |
2000
|
| 8.967 |
3000
|
| 10.283 |
3500
|
| 11.277 |
3900
|
Fringe fields
- NIM article on the TOSCA calculations of SHMS fringe fields effects on the beam and mitigation.
- For SHMS at 5.5 degrees, Drawing.
- 2.065 inch diameter pipe fills HB cut-out.
- Transition to 2.875 inch diameter pipe at 98 inches (250cm). Mechanical exit of HB is around 230cm. Pipe diamter set by the Q1 cut-out.
- Transition to 5.5 inch diameter pipe at 165 inches (419cm). So smallest opening is 2.875/165/2 = +/-8.7mr .
- For HMS at 10.5 degrees, Drawing of beam pipe region.
- Notch in Q1 determines pipe diameter of 1.9 inches.
- Transition to 2.875 diameter pipe is where the support is possible.
- Presentation with more drawings of beam pipe configurations.
- The integral Bdl along the beam line for different angles of SHMS set at 3900A with and without wedges.
| SHMS angle |
HB Bdl (As built) |
HB Bdl ( with wedges)
|
| 5.5 |
0.117 Tm |
0.070
|
| 10 |
0.035 |
0.0109
|
- At 10 deg the fringe field from Q1 and Q2 is very small. theta_b = .299*.0109/11. = 0.0003 and displacement at the beam dump (50m upstream) is .0003*5000 = 1.5cm
SHMS Q1 mapping
- Report on the analysis of the Q1 mapping data.
- Plot of B versus I compared to OPERA.
- Table of momentum versus current:
| Momentum (GeV) |
Current (A)
|
| 6 |
1228
|
| 8 |
1672
|
| 10 |
2169
|
| 11 |
2454
|
HMS and SHMS Dipoles
SLITS and COLLIMATORS
SHMS Detector Positions
SHMS Characteristics
SHMS Drawings of magnets
Study of the SHMS resolution
- Study of the SHMS resolution.
Old HMS information
SNAKE
Moved Snake section here.
