Constants History

SLAC	PEP-II
BABAR
SLAC<->RAL

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The table lists the constants changes that have been implemented. There are two sets of constants: Front-end(online) and Back-end(offline). Front-end means that the constants are applied online so that the raw data (.xtc files) already has them applied. Linearity refers to the electronics linearity constants. Back-end refers to the offline constants that are applied in OPR (IR-2 conditions database). Backend constants can applied retro-actively. Eg. On September 10th we installed back-end constants that are applicable to any data taken after 14th May. However any data processed before 10 September will not have these constants applied.

CONSTANTS CHANGES
Date Installed	Run Validity	Front-end change	Front-end change details	Back-end change	Back-end change details
Apr 28 99	2031-2350	Yes	Best guess gains, digicut 5 MeV	Yes	All set to 1.0
May 14 99	2351-7339	Yes	MIP/QC gains	No	No
June 10 99	2351 onwards	No	No	Yes	Mip/QC correction applied for all runs from 2351
Aug 12 99	7340-8354	Yes	New linearity, Digicut 2.5 MeV,new gains from bhabha's or MIP/QC where no bhabha	Yes	All Set to 1.0
Aug 24 99	8405-9080	Yes	New linearity	No	No
Sep 7 99	9081-9726	Yes	New linearity	No	No
Sep 10 99	2351 onwards	No	No	Yes	Source constants: Valid for all previous front-end constants from 14th May (run 2031) onwards. Data processed before 10 September has back-end constants as above. Data processed afterwards has valid source constants for all dates.
Oct 19	9839-9905	Yes	New Linearity, New gains from source constants	Yes	Incorrectly set 9839-9905
Oct 22	9906 onwards	No	No	Yes	All set 1.0 start validity date 00:00:00 Oct 21 99

Colin Jessop

Last modified: Mon Oct 20 16:00:00 PDT 1999