Difference between revisions of "How-to"

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(Magnets)
(Magnets)
Line 57: Line 57:
  
 
If you need to change polarity, first ramp the magnet to 0 [A], and then you can change the polarity. After this change, you will need to ramp the magnet to maximum again.  
 
If you need to change polarity, first ramp the magnet to 0 [A], and then you can change the polarity. After this change, you will need to ramp the magnet to maximum again.  
 
+
*For HMS magnets, the current limits are shown in the following table:
 +
{|border="1" align="center"
 +
!HMS Magnet !!  Max current [A]
 +
|-
 +
!Q1 !! 1000
 +
|-
 +
!Q2 !! 600
 +
|-
 +
!Q3 !! 600
 +
|-
 +
!Dipole !! 3000
 +
|}
 +
Do not exceed these limits! HMS magnets are put "on loop" by going 200 A above the desired set point and then reducing current to desired (see pdf below). The currents for the HMS quads for a desired momentum are obtained by running the field03 program located at FIELD/field03. The HMS dipole momentum has new NMR measurements and can be obtained from the following command:
 +
go_magnet_HMS_current P
 +
where P is the momentum in GeV. This will return the current and the recommended NMR setting.
 
*[[Spectrometer Magnets]]
 
*[[Spectrometer Magnets]]
 
*[https://hallcweb.jlab.org/DocDB/0008/000837/001/HMS_cycling_2007.pdf How to cycle the HMS quad magnets]
 
*[https://hallcweb.jlab.org/DocDB/0008/000837/001/HMS_cycling_2007.pdf How to cycle the HMS quad magnets]

Revision as of 17:41, 8 December 2017

NOTE: If you can't solve the problem in 1 hour you MUST then contact the Run Coordinator! (See also Experts on call)

How-to's

Magnets

  • Magnet screen is brought up on any hcdesk machine using
 % go_magnets
  • For the Fall 2017 run, the SHMS magnets can be set by current from the desired momentum in [GeV]. From any computer, run:
go_magnet_SHMS_current P

where P is the desired momentum in [GeV]. This will return the current that each SHMS magnet should be set to. The formulas and program are in sync with the repository. For precision physics data-taking, the magnets should be put "on loop". Turn off the beam prior to ramping the magnet and putting on loop. The procedure to put the magnet on loop is described here:

Ensure beam is off.
1. Select polarity for electrons or positrons in the magnet gui.
2. Ramp each magnet to the maximum current (see table below for SHMS).
3. Ramp each magnet down to its desired current (the output of go_magnet_SHMS_current). 
SHMS Magnet Max current [A]
HB 3600
Q1 2400
Q2 3660
Q3 2480
Dipole 3440

If you need to change polarity, first ramp the magnet to 0 [A], and then you can change the polarity. After this change, you will need to ramp the magnet to maximum again.

  • For HMS magnets, the current limits are shown in the following table:
HMS Magnet Max current [A]
Q1 1000
Q2 600
Q3 600
Dipole 3000

Do not exceed these limits! HMS magnets are put "on loop" by going 200 A above the desired set point and then reducing current to desired (see pdf below). The currents for the HMS quads for a desired momentum are obtained by running the field03 program located at FIELD/field03. The HMS dipole momentum has new NMR measurements and can be obtained from the following command:

go_magnet_HMS_current P

where P is the momentum in GeV. This will return the current and the recommended NMR setting.

SHMS Detectors

HMS Detectors

Hall C target

Hall C target configuration for Spring 17 running

Legacy Documentation