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« December 2018 »

Experiment - 8Pi - Tuning Tips

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through the slits & collimator --TA, Feb. 2011 & corrected by JA

1.  Tune the beam to ILE1A:FC1.  Beam at ILE1A:RPM1 should be centered and roughly symmetric (see Figures 1, 2); (RPMs' reference file 2009.12.02.13:41:51.snap, OLIS-->8PI reference tune 091202_1400.snapios8pi [Mike Trinczek]).  For ILE1A:XCB1 through ILE1A:Q10, set quads, benders, and slits to theoretical values and steering to zero-effect. 

8PI beam envelope rough rpm locations ILE1A:RPM1

Figure 1:  ILE1A (8PI) Beam Envelope showing rough RPM location            Figure 2:  ILE1A:RPM1 reference (elog 2009-12-02 14:12:28)


2.  Open ILE1A:(X/Y)SLIT4A device pages.  Send the beam to ILE1A:FC6.  Aim for 100% Transmission (Tx) while centering the beam on & focusing it through the 5mm slits using ILE1A:XCB1->ILE1A:B4.  Occasionally check ILE1A:RPMs(4/4A) (compare w/ Figures 3, 4) and verify that the profiles roughly match the expected envelope in Figure 1. It is OK to take ILE1A:Q1->ILE1A:Q4, as well as downstream quads, well off of theory. We don't expect those quads to stay right at theory because they are needed to 'match' the beam into 8pi.


Figure 3:  ILE1A:RPM4 reference (elog 2009-12-02 14:12:28)                        Figure 4:  ILE1A:RPM4A reference (elog 2009-12-02 14:12:28)


3.  Ensure ILE1A:IV8 is open (if not, consult w/ experiment before opening).  Open ILE1A:(X/Y)SLIT8 device pages.  Send the beam to ILE1A:FC10.  Aim for 100% Tx while centering the beam on & focusing it through the 13.2/11mm slits.  Ideally, attempt to achieve this using only devices past ILE1A:(X/Y)SLIT4A.  Occasionally check RPM8 (comparing w/ Figure 5) and verify that the profiles roughly match the expected envelope (Figure 1).


Figure 5:  ILE1A:RPM8 (elog 2009-12-02 14:12:28)


4.  Open ILE1A:COL12D & ILE1A:FC12 device pages.  Confirm w/ experiment that ILE1A:FC12 is installed (removable cup), and that the cable for ILE1A:COL12D is connected (to read collimator current).  Remove all upstream Faraday cups.  Aim for max Tx while minimizing beam on the collimator, ideally using only devices past ILE1A:(X/Y)SLIT8.


5. Save the tune and check the ILE1A:FC12/FC1 Tx.


6.  Revisit all ILE1A optics while watching the current on ILE1A:FC12.  Iterate through them and maximize transmission from ILE1A:FC1 to ILE1A:FC12.  If no improvements are possible, restore the save tune in (5.) above.  If improvements are made, re-save the tune.


7.  Document the tune (RPM'S, snapshot, etc).

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