Calculating dQs

After the LOCO results are loaded into Table 6 of the Booster ramp cards for machine studes, it is found that the efficiency is about 2% lower than the operational lattice. Tuning Booster with the LOCO lattice using the dQs is very tedious and will probably take a very long time to get to the same efficiency as the operational lattice stored in Table 1.

The goal of calculatedQs is to try to minimize any tuning by putting back the tunes that is found in the operational table 1. The method is as follows:

The dQs of the LOCO lattice are used to "zero" out the average QL and QS currents. i.e.

dQL = - (average QL of Table 6)
dQS = -(average QS of Table 6)

The above should zero out the "tunes" on average in Booster.

Then the average of the QL and QS currents of the operational table 1 is added, i.e.

dQL = - (average QL of Table 6) + (average QL of Table 1)
dQS = - (average QS of Table 6) + (average QS of Table 1)

In principle, this should reproduce the Table 1 tunes in the LOCO lattice.

Obtaining the source code

The source code can be downloaded here:

git clone


Builds on MacOSX 10.9.x and LINUX on CLX cluster are supported


Edit the Makefile to put in the appropriate paths if necessary. The Makefile has been set up so that it knows whether it is run on a Mac or on the CLX cluster.



dq should be created. Move dq to your local path.

Checking the configuration

dq -h

The output should look something like this

~/expt/booster/loco_new/calculatedQs@xanadu% dq -h
dq version 1.0-0-g5f658b3-1

generic options :
  -h [ --help ]         this message
  -1 [ --1 ] arg        Table 1 file
  -6 [ --6 ] arg        Table 6 file
  -o [ --ofile ] arg    output file for LoaddQs.acl
  -d [ --debug ]        enable debugging
  -v [ --version ]      print version

Creating the dQ.txt file

The requirements are that you have the following files:

  • quad1.txt that was generated by ReadQuadSettings.acl by editing it to point to Table 1.
  • quad6.txt that was generated by ReadQuadSettings.acl by editing it to point to Table 6.

dq will generate a dQ.txt file that is compatible with LoaddQs.acl with the following command

dq -1 quad1.txt -6 quad6.txt -o dQ.txt

The files that is generated is

  • dQ.txt