========================================================================= Procedures for machine studies measuring beam size using sextupoles ========================================================================= 18 February 2021 jac. Updated 2 November 2021. --------------------------------------------------------------------------------------------- * To start gdl vbsm monitoring (SW): >gdl vbsm_pos * To start gdl monitoring of DTT tunes(SW,JAC): >gdl dtt_tunes (the .inp files must be in the local directory) * To read the tunes once (JAC): >/home/critten/linux_lib/production/bin/read_dtt_freq BEWARE: if a .inp file of the same name exists in the directory /nfs/cesr/online/acc_control/program_info/gdl/ it will be chosen by default over the .inp file in the local directory. This can be circumvented with, for example, >gdl ./vbsm_pos --------------------------------------------------------------------------------------------- * To perform a coarse (0+-3000cu) scan of a single quadrupole * with pauses to take TbT data CesrV> call k2scan_coarse.cesrv [sextupole index 8-10, 12-45, 47, 52, 54-89, 91] --------------------------------------------------------------------------------------------- * To perform a fine (-3000cu to +3000cu in 11 steps) scan of a single sextupole * with pauses to take TbT data CesrV> call k2scan_fine.cesrv [sextupole index 8-10, 12-45, 47, 52, 54-89, 91] --------------------------------------------------------------------------------------------- * To start the calibration loop over all sextupoles including pauses * to take TbT data (DCS, JAC): >/home/dcs16/linux_lib/production/bin/cesrv_cl calsex_loop.cesrv This CesrV script is available here: https://www.classe.cornell.edu/~critten/chessu/ms_sextupoles/calsex_loop.cesrv --------------------------------------------------------------------------------------------- * To take one set of turn-by-turn orbit data (VK): >cbpm_tbt_positrons Choose 8192 turns. If the data-taking is too time-consuming, use 4096 turns. The DTT can be locked during the data-taking. * To take a certain number of TbT data sets, currently three (VK): > source /home/critten/ms_sextupoles/take_TBT.sh NB: This script will write zero's in the field "The locked freq" when lock has been lost. The values from the digital tune tracker register continue to update. --------------------------------------------------------------------------------------------- * New version of CesrV which writes both phase and orbit data (DCS): >/home/dcs16/linux_lib/production/bin/cesrv_cl CesrV documentation is here (JAC): https://cesrwww.lepp.cornell.edu/wiki/CESR/CESRV To calibrate a sextupole, for example: CesrV> calib sex_09aw [cu1] [cu2] phase_tbt ! cu1, cu2 optional, see below. If cu1 and cu2 not present, the sextupole settings used are +- half this value CesrV>set logic%sex_calib_delta_cu = 30000 The equivalent value used during the 10/28/2002 calibrations was 8000. Those calibrations were accurate to about rms 7%. Number of bump settings for each sextupole CesrV>set logic%sex_calib_n_bump_set = 2 This dQ value is used to set the closed bump magnitude. Leave it at default CesrV>set logic%sdQ_max_quad_calib = 2e-2 Nearly all sextupoles have length 0.272 m and dk2/dcu = 1.53e-4 So the range in k2L is from -1.25 to 1.25 m^-2. --------------------------------------------------------------------------------------------- * The digital tune tracker must be locked during the sextupole calibrations Detailed information here (JSh): https://www.classe.cornell.edu/~critten/chessu/ms_sextupoles/DTT_operation.pdf If the settings have been tuned, then this shell command will suffice to lock the tunes (JSh): >tt_lock_acq --------------------------------------------------------------------------------------------- *Detailed info on sextupole calibration dated (28 Nov 2018) here (JAC): /nfs/cesr/online/machine_data/constants/calib/sextupole.cal --------------------------------------------------------------------------------------------- *Sextupole settings as of 15 Feb 2021) are here (JAC): https://www.classe.cornell.edu/~critten/chessu/ms_sextupoles/cesrv_sextupoles_15feb2021.txt This file was obtained with CesrV>&show sex --------------------------------------------------------------------------------------------- * In addition to the gdl monitoring described above, newin can also be used. * To start newin vbsm monitoring (JAC): >newin newin_vbsm * To start newin monitoring of DTT tunes(JAC): > newin dtt_tunes * To start newin monitoring of DTT tunes and bunch current(JAC): > newin newin_dtt_current * To see which nodes are being logged, for example (SBP): > whlog ttrack --------------------------------------------------------------------------------------------- * To set/read individual sextupole settings in cu: $fff vxputn csr_sext_cur 8 8 $fff vxgetn csr_sext_cur 8 8 These can be done with spawn commands in CesrV --------------------------------------------------------------------------------------------- * In addition to the gdl and newin monitoring, dtp can also be used to write a tune logging file: > dtp dtt_tunes.ctl to accept the default data file name. Choice TD to begin taking data. The control file (dtt_tunes.ctl) and the data file (DTT_TUNES.hh-mm) are found in the directory /nfs/cesr/online/acc_control/program_info/dtp --------------------------------------------------------------------------------------------- * Yet another way to record DTT tunes, currently set up for every 3 seconds(VK): > source /home/critten/ms_sextupoles/take_tunes_with_rms.sh The output file can be converted to a simpler format with >/nfs/opt/root-6.13.02.sl7/bin/root -l read_and_plot_tune.C by changing the input file name in the .C file.