This is describing the 900 GeV collisions menu. Due to the extremely low pileup (PU ~ 0.05), the HLT can take high rates. We expect an HLT rate up to
45 kHz! This does not apply normally!
- The ZeroBias rate is 11.2 kHz per colliding bunch. The expected MinimumBias (PU ~ 0.05) rates are of the order of 250 - 600 Hz per colliding bunch.
The menu primarily writes out ZeroBias (all colliding bunches) and MinimumBias (pass though of
L1_MinimumBiasHF0_AND_BptxAND
). The ZeroBias is split between 20 datasets while the MinimumBias is split between 10 in order not to surpass per dataset size limit. It also runs paths necessary for AlCa. We are also running the nominal HLT physics paths as a test, even though they have a very low rate.
The correct choice of column will depend on where we are in commissioning the trigger system and the number of bunches in the machine. Therefore the HLT DOC will tell you the correct column, please contact them if you are unsure.
Side Note: As a rule of thumb (up to 4 colliding bunches) the random trigger rate should be set (by the DAQ shifter) to 10 kHz/colliding bunch, in order to reduce the ReTri deadtime, which protects the tracker from regular triggers.
- For 2 colliding bunches, the random trigger rate should be set to 20 kHz.
- Therefore, the L1 input rate is the sum of the ZeroBias rate (22.5 kHz, for 2 colliding bunches) and random trigger rate (20 kHz) = 42.5 kHz.
Side Note 2: During beam commissioning, and particularly during unstable collision, there may be possible high rates from the JetHT Primary Dataset.
A good indicator of this happening is if the rate of
HLT_AK8PFJetFwd15
goes above 2 kHz.
If you observe this is is the case, go to column 16 (ZeroBiasHalfMinBias), since it also prescales jet paths by a large factor.
Raise a warning about this in the Shifters+DOCs Mattermost room.
Column Description
Please confirm with the HLT DOC (165575 or 66278) which column to be in, as it will be changing during the commissioning period. The recommended column is column 1 ZeroBiasMinBias
for the stable fills with n(Bunches) ≤ 4. The default column is set to 0 Emergency
, which disables output, and should be changed during actual collisions
A summary of each prescale column is given in the following format:
ZeroBias
un/
prescaled; MinimumBias
un/
prescaled or
disabled; AlCa paths
enabled/
disabled; physics paths
enabled/
disabled
- The prescale values are given in the format (L1_PS*HLT_PS)
- The expected rates can be calculated with the expected Zero/MinimumBias rates (above) and their corresponding prescale
column 0: Emergency (default column)
- It is a column for standby use. It only writes out randoms and ECAL and HCAL calibration triggers, i.e. it effectively disables the CMS output.
- Therefore the rate will be very small so as not to risk accidentally overloading T0
- It is now the default column as there is concern in other collision columns, the LHC could potentially give us a very high rate when they are commissioning with circulating coinciding bunches.
- During actual collisions you definitely don't want to be in this column!
- ZeroBias prescaled by (1103*100); MinimumBias disabled; AlCa paths disabled; physics paths disabled
- Note:
L1_MinimumBiasHF
prescaled by 500 @ L1T
- The
DST_Physics_v7
(PS=1) and HLT_Random_v3
(PS=1800) triggers and HLT_EcalCalibration
and HLT_HcalCalibration
are enabled
column 1: ZeroBiasMinBias (recommended column for n(Bunches) ≤ 4)
- Writes out all ZeroBias and MinimumBias datasets, while all physics paths are unprescaled (except of those seeded by
L1_Random
or L1_ZeroBias
)
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
column 2: ZeroBias
- Writes out the ZeroBias but not MinimumBias
- ZeroBias unprescaled; MinimumBias disabled; AlCa paths enabled; physics paths enabled
column 3: MinBias (recommended column for 4 < n(Bunches) ≤ 8)
- Writes out the MinimumBias but prescales the ZeroBias by a factor 2, when we can not record all events (expected when 4 < n(Bunches) ≤ 8)
- ZeroBias prescaled by (1*2); MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
column 4: MinBiasMedium (recommended column for n(Bunches) > 10)
- Writes out the MinimumBias but prescales the ZeroBias by a factor 6, when we can not record all events (expected when n(Bunches) > 10)
- ZeroBias prescaled by (3*2); MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
- Note: PixelClusters MinBias paths seeded by 'OR' of unprescaled
L1_MinimumBiasHF0_AND_BptxAND
and prescaled ZeroBias
column 5: MinBiasHigh
- Writes out the MinimumBias but prescales the ZeroBias by a factor 10, when we can not record all events (expected when n(Bunches) > 24)
- ZeroBias prescaled by (5*2); MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
- Note: PixelClusters MinBias paths seeded by 'OR' of unprescaled
L1_MinimumBiasHF0_AND_BptxAND
and prescaled ZeroBias
column 6: MinBiasVeryHigh
- When we can no longer take all
L1_MinimumBiasHF0_AND_BptxAND
events at HLT
- HLT pass through for
L1_MinimumBiasHF0_AND_BptxAND
prescaled by factor 5
- relies on
HLT_PixelClusters_WP2
to collect data
- ZeroBias prescaled by (11*10); MinimumBias prescaled by 5; AlCa paths enabled; physics paths enabled
- Note: PixelClusters MinBias paths seeded by 'OR' of prescaled
L1_MinimumBiasHF0_AND_BptxAND
and prescaled ZeroBias
column 7: ZeroBiasMinBiasReducedReco
- Same as column 1 but disables physics HLT paths
- equivalent to the minimal menu with only ZeroBias + MinimumBias + AlCa
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths enabled; physics paths disabled
column 8: ZeroBiasReducedReco
- Same as column 2 but disables physics HLT paths
- ZeroBias unprescaled; MinimumBias disabled; AlCa paths enabled; physics paths disabled
column 9: MinBiasReducedReco
- Same as column 3 but disables physics HLT paths
- ZeroBias prescaled by (1*2); MinimumBias unprescaled; AlCa paths enabled; physics paths disabled
column 10: ZeroBiasMinBiasNoReco
- Same as column 1 but disables all reconstruction
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths disabled; physics paths disabled
column 11: ZeroBiasNoReco
- Same as column 2 but disables all reconstruction
- ZeroBias unprescaled; MinimumBias disabled; AlCa paths disabled; physics paths disabled
column 12: MinBiasNoReco
- Same as column 3 but disables all reconstruction
- ZeroBias prescaled by (1*2); MinimumBias unprescaled; AlCa paths disabled; physics paths disabled
column 13: L1BunchMaskNoReco
- Same as column 14 but disables all reconstruction
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths disabled; physics paths disabled
- Note: ZeroBias =
HLT_ZeroBias
seeded by L1_AlwaysTrue
* ALGOBX_MASK
column 14: L1BunchMask
- Output ZeroBias but instead of using the ZeroBias trigger, it uses
L1_AlwaysTrue
masked by the ALGOBX_MASK
parameter which allows us to manually specify the bunches to trigger on
- Used in case of a problem with the BRIL system and for testing and should only be used under expert advice
- MinimumBias is disabled although
HLT_PixelClusters_WP2
paths are still active
- Disables all L1 seeds except
L1_AlwaysTrue
and L1_CDC_SingleMu_3_er1p2_TOP120_DPHI2p618_3p142
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
- Note: ZeroBias =
HLT_ZeroBias
seeded by L1_AlwaysTrue
* ALGOBX_MASK
column 15: ZeroBiasMinBiasHighReco
- Same as column 1 but with scouting path enabled (
DST_Run3_PFScoutingPixelTracking
) enabled
- ZeroBias unprescaled; MinimumBias unprescaled; AlCa paths enabled; physics paths enabled
column 16: ZeroBiasHalfMinBias
- Same as column 1 but ZeroBias is prescaled by 2 and MinBias by 4 at HLT level. This means that it will write out half of ZeroBias and a quarter of MinBias data.
- ZeroBias prescaled by (1*2); MinimumBias prescaled by (1*4); AlCa paths enabled; physics paths enabled
- Jet paths prescaled by a large factor
column 17: ZeroBiasQuarterMinBias
- Same as column 1 but ZeroBias is prescaled by 4 and MinBias by 8 at HLT level. This means that it will write out a quarter of ZeroBias and an eighth of MinBias data.
- ZeroBias prescaled by (1*4); MinimumBias prescaled by (1*8); AlCa paths enabled; physics paths enabled
- Jet paths prescaled by a large factor