DownScaleDst file format description

Here is the brief list of what are in the Down Scale DST files:

• Basic event information, like Event Id, refMult, etc.
• Calculated event plane components X and Y from TPC and FTPCs (not corrected)
• Information to get event plane from ZDC SMD.
• V0 tracks with applied cuts to select Lambda / Anti-Lambda / K0Short
• Primary tracks information.
  For p_t < 1.8 GeV each 50th track from FTPCs and each 100th from TPC are taken.
  For p_t > 1.8 GeV all tracks are taken.

NOTE: There is no event cuts - all events are taken.

Why we need DownScaleDst file?

The main advantage of DownScaleDst files is smaller size compared to STAR MuDst files. It is about 50 times smaller than those of MuDst files. The smaller size results in faster data analysis.

Down Scale files could be used in flow analysis of charged or strange particles, high pt correlations.

The list of DownScaleDst TTree leaves (with some comments on "non-standard" variables)

DownScaleDst TTree

mZdcAdcAttentuatedSumWest
mZdcAdcAttentuatedSumEast
mZdcSmdWest[16]
mZdcSmdEast[16]
mCtbMultiplicity
mPrimaryVertexX
mPrimaryVertexY
mPrimaryVertexZ
mX[2][3][2][31] // X component of the event plane vector
mY[2][3][2][31] // Y component of the event planevector
// Q[charge][harmonic][subEvent][etaBin]; harmonic = 0 => multiplicity;
//ETA BINS: FTPCE -4.1 < eta < -2.5 (8 bins); FTPCW 2.5 < eta < 4.1 (8 bins); TPC -1.5 < eta < 1.5 (15 bins)
mEventId
mRunId
mNumberOfGoodPrimaryTracks
mNumberOfV0Tracks
mNumberOfPrimaryTracks
mNominalTriggerId[32]
mCentrality // centrality calculated according to the standard STAR refMult regions
mRefMult
mRefMultEtaWide // refMult calculated from tracks with wide eta cut |eta|<0.8

V0 branch

V0.mTypeOfStrangeParticle // 0 Lambda; 1 Anti-Lambda; 2 K0Short
V0.mMomPos.fX
V0.mMomPos.fY
V0.mMomPos.fZ
V0.mMomNeg.fX
V0.mMomNeg.fY
V0.mMomNeg.fZ
V0.mPtV0
V0.mPtPos
V0.mPtNeg
V0.mIsPosPrimary // need to remove auto correlations if the pos V0 track is in Event Plane
V0.mIsNegPrimary // if the neg V0 track is in Event Plane v0IsPrimary = etaBin+1-(nEtaTotal+1)*(1-subEvent)
V0.mPseudoRapV0
V0.mPseudoRapPos
V0.mPseudoRapNeg
V0.mMassLambda
V0.mMassAntiLambda
V0.mMassK0Short

Primary branch

Primary.mId
Primary.mCharge
Primary.mMaxPoints
Primary.mFitPoints
Primary.mTrackInEventPlaneFlag // need to remove auto correlations if track is in Event Plane TrackInEventPlane = etaBin+1-(nEtaTotal+1)*(1-subEvent)
Primary.mDEdx
Primary.mPt
Primary.mPhi
Primary.mEta
Primary.mDcaGlobal.mX1
Primary.mDcaGlobal.mX2
Primary.mDcaGlobal.mX3