E-rhic-ir-l mailing list

[Bill Christie <christie AT bnl.gov>]

Dear All,
    Below please find the minutes from today's (1/5/18) eRHIC IR Design 
mtg. The presentations discussed are attached to these minutes.
    Greetings,
        Bill

    eRHIC IR Design meeting minutes for 1/5/18.
    ------------------------------------------------------------
    Attending: Elke, Bob, Holger, Charles, Alexander, Bill

* The meeting started with a walk through of a presentation by Bob. The 
title of the file used was "1712-update-corrected-2.pdf"
    - There is a version 3 of this information which hasn't been 
circulated.
    - Discussion of the synchrotron radiation fan. As will come up 
again in this meeting, there is a desire and benefit to reducing the 
"stay clear" acceptance for the fan from 15 to 13.5 sigma.
        - Bob brought up that, as shown in slide 7 of his presentation, 
that the fan in Y (vertical) is much smaller than in x, Christoph had 
some concern about the extent or stay clear area for the vertical fan. 
Need Christoph to understand what this concern is.
    - Elke expressed her worry/concern about the synchrotron fan 
striking something like the first downstream magnet for the electron 
beam, scattering back into the detector, and damaging detector elements. 
Emphasized need to be careful about this.
    - Elke also asked how the 15 / 13.5 sigma compared to possible 
movements of the beam due to the injection kicker or other possible 
excursions due to malfunctions or mis-stearing of the beam.
    - In response to a question by Bill, Bob indicated that the beam 
and magnet parameters shown in this v2 of the talk have been checked and 
corrected since our last face to face mtg, but the values in the v3 have 
been checked even more strenuously. Bob also points out that many of 
these parameters could change again, depending on the outcome of the 
discussions between Ferdi and Christoph dealing with what constraint is 
decided upon for the stay clear synchrotron fan acceptance.
    - Alexander will check on the simulations for the parameter set 
that Bob has sent out for the High divergence, high luminosity setup. 
These parameters are in the file "1712-forward hadron HD file.txt".

* We then walk through the two slide presentation sent out by Charles. 
The name of the file is "IR discussion 1-5-18.pdf"
    - Charles is currently using 30 cm for the length of the warm to 
cold (WCT) transition, as shown in slide 1.
    - He shows the end of the central detector beam pipe fixed just 
upstream of this warm to cold transition. If this is indeed what is 
implemented, he thinks the bellow shown in the WCT can be as short as 20 
cm.
    - Brief discussion about the geometry, and available space for a 
flange, on the downstream hadron beam end of the detector.
    - Charles will make a figure, similar to slide 1 on today's 
presentation, showing a possible geometry for this outgoing hadron beam 
end of the central beam pipe. This will aid discussion of this topic in 
the next meeting.
    - A brief discussion on how one might bake out the central detector 
beam pipe, and some of the complications involved. This topic clearly 
needs more discussion, which will get started next week.
    - This discussion was coupled to the discussion can pumping of the 
IR been integrated in the design.

* We then move on to a discussion of Holger's presentation. The name of 
the presentation file is "2018-01-05_Q1PR.pdf"
    - General comment by Holger that the design, as shown in slide 2, 
gets simpler if the synchrotron fan stay clear acceptance is allowed to 
decrease from 15 to 13.5 sigma. This acceptance is shown by the ellipse 
in slide 2.
    - In slide 3 Holger points out that with the smaller fan 
acceptance, the beams can be separated by more soft iron, and as shown 
in the slide the iron doesn't saturate in the region between the p and 
e- beams in the magnet.
    - If we can go with this fan acceptance (13.5 sigma) then all looks 
realizable/doable.

* Elke asks where the synchrotron fan geometry comes from: from 
Christoph? From Jlab group? ...
    - Bob replies that the geometry for the fan can be determined from 
the electron beam profile and trajectory. The magnitude of the radiation 
in the fan has to come from something like Christoph's 
calculation/simulation. Elke points out that the Light Source people on 
site likely have more modern code for these calculations.

* Elke indicates that she has agreed to generate some text for Ferdi, 
for inclusion in the PreCDR summary report that describe the constraints 
on the IR design that result from the criteria imposed by the physics 
program. Asks if anyone has a version of such text. Bob has some very 
rough text, but not likely sufficient.
    - Elke will generate a draft for this text in MS Word format, and 
send it around for comment. Once final she'll convert to LaTec for the 
report.

* Brief discussion about where, relative to the center of the detector, 
along the beamline, the p and e- beams separate either into physically 
separate pipes, or into electro magnetically shielded regions. Some back 
and forth but no firm conclusion at this point. The decision of the 
synchrotron fan will impact this.
     - this will also influence what pumping is the best solution.

* Discussion and agreement that we should have the next meeting next 
week, Friday 1/12/18.
    Preliminary Agenda for 1/12/18 mtg:
    - Conclusion from the discussion between Ferdi and Christoph about 
the stay clear acceptance for the synchrotron radiation fan.
    - Short presentation and discussion of the figure that Charles will 
generate and send out showing a proposed geometry for the outgoing 
hadron end of the central beam pipe.
    - Alexander will give a presentation on status of implementing the 
patest beam and magnet parameter file into the simulations. He will also 
discuss status of importing a "STEP" file from charles that details the 
central beam pipe, and outgoing electron side geometry, with the WCT, 
into the simulation framework.
    - Wasn't discussed at meeting, but added by note taker, discussion 
of the text from Elke regarding IR design constraints imposed by physics 
program.

                End of meeting

Attachment: 1712-update-corrected-2.pdf
Description: Adobe PDF document

Attachment: IR discussion 1-5-18.pdf
Description: Adobe PDF document

Attachment: 2018-01-05_Q1PR.pdf
Description: Adobe PDF document

## December 22, 2017 High Divergence forward hadrons at 275 GeV/c

## using Palmer's file is bet87h labelled nnp3h.tex

## The detector solenoid is not included

## note that these values are not identical to those in the current lattice 
(see page 5 above)

## ----------------------------------------------------------

## Initial conditions at IP 

##

## beta*_x  beta*_y  g emit_x g emit_y  angle_x  angle_y

##  [m]      [m]      [nm]     [nm]     [mrad]   [mrad]

##

  0.9440   0.0420     16.1000    6.1000      22      0  

## -----------------------------------------------------------

## magnet parameters 

##

##name  center_z center_x center_y radius   length   angle      B      
gradient

##           [m]      [m]      [m]      [m]      [m]    [mrad]     [T]     
[T/m]

##

  B0pf    5.599  -0.0132    0.00   0.1700    1.200   -22.00   -1.300      
0.00  

  Q1pf    7.548   0.0040    0.00   0.0420    1.500     0.00    0.000   
-134.32  

  Q2pf   12.197   0.0201    0.00   0.1050    2.400    -2.00    0.000     
44.02  

  B1pf   15.396   0.0400    0.00   0.1350    3.000     0.00   -4.574      
0.00  

## x=0, z=0, y=0 is at the center of the IP

## The z axis is aligned with the initial mean hadron direction

## Only the magnets close to the IP are given, those further away must come 
from the 

## lattices

## 
------------------------------------------------------------------------------

##

## parameters at the Roman Pots for HA2

##

##loc     Z      beta_x   beta_y   adv_x    adv_y    Disp 

##        [m]    [m]      [m]      rad/pi    rad/pi   {m}

##

  R1    36.00   1105.2   197.73   0.488    0.53    0.343 

  R2    39.00   1188.7   174.19   0.489    0.54    0.387 

##

##===============================================

## 10 sigma beam outlines and magnet apertures for 275 GeV protons in above 
HD case

## These numbers use the above initial values, rather than the current 
lattice  

##

## name(i)  thetax    L(m)  cenx(cm)  ceny topx(cm) botx  topy(cm)  boty 
betax(m)  betay   magc(cm) top(cm) bot(cm)

  B0( 3 )   0.0000    5.0    0.00   0.00    0.66   -0.66    1.90   -1.90    
0.66    1.90     0.00    17.00   -17.00

  gap      1.7018    6.2    0.11   0.00    0.92   -0.71    2.32   -2.32    
0.82    2.32      0        0        0

  Q1( 5 )   1.7018    6.8    0.21   0.00    1.10   -0.69    2.53   -2.53    
0.90    2.53     0.40     4.60    -3.80

  gap      1.5466    8.3    0.45   0.00    1.70   -0.80    2.63   -2.63    
1.25    2.63      0        0        0

  Q2( 7 )   1.5466   11.0    0.86   0.00    3.08   -1.36    2.00   -2.00    
2.22    2.00     2.25    12.75    -8.25

  gap      3.1347   13.4    1.42   0.00    4.17   -1.32    1.69   -1.69    
2.75    1.69       0        0        0

  B1( 9 )   3.1347   13.9    1.58   0.00    4.36   -1.20    1.67   -1.67    
2.78    1.67     4.00    17.50    -9.50

##