Triggering with CASTOR

P R E L I M I N A R Y

Trigger Bits

Trigger Bits are logical true/false conditions that CASTOR can send as input to the Global Trigger Logic. Physics Trigger Bits can be combined with other conditions from CMS into a Trigger Algorithm, while technical Trigger Bits bypass the Global Trigger Logic and enter the Final Or Logic directly.

Definition of variables

  • Ehad,i = total energy deposited in the hadronic readout units of one φ-sector (i = 1, ..., 16)
  • Ehad,tot = Σi=116 Ehad,i
  • Eem,i = total energy deposited in the electromagnetic readout units of one φ-sector (i = 1, ..., 16)
  • Eem,tot = Σi=116 Eem,i
  • Etot,i = Eem,i + Ehad,i
  • Etot = Ehad,tot + Eem,tot
  • T2tracki = true if at least 1 T2 track in front of φ-sector i

Trigger Bit table for proton-proton running

Trigger Bit Condition Type
CASTORetot1 Etot > noise technical
CASTORetot2 Etot > threshold physics
CASTORrapgap Etot < noise physics
CASTORfwdjet1 Ehad,i > 750 GeV technical
CASTORfwdjet2 Ehad,i > 500 GeV physics
CASTORfwdelec1 Eem,i > threshold AND Ehad,i < noise AND T2tracki physics
CASTORfwdelec2 Eem,i > 250 GeV AND Ehad,i < 5 GeV AND T2tracki AND Eem,j > 250 GeV AND Ehad,j < 5 GeV AND T2trackj technical
CASTORfwdgamma Eem,i > threshold AND Ehad,i < noise AND NOT(T2tracki) physics

Note:

  • noise levels and thresholds may be different for different Trigger Bits
  • track information is obtained directly from T2 through a private cable

Trigger Bit table for heavy ion running

Trigger Bit Condition Type
? Ehad,tot / Eem,tot > ratio ?
? Etot,i / (Etot/16) > ratio ?
? Ehad,i / (Ehad,tot/16) > ratio ?

Trigger Algorithms

Trigger Algorithms are logical conditions based on information obtained by all CMS-components capable of providing L1 trigger signals. Each algorithm can be individiually prescaled before entering the Final Or Logic. The Global Trigger allows 128 Trigger Algorithms and xxx Technical Triggers with a total L1 rate of 100 kHz.

Trigger Algorithm table for proton-proton running

Physics analysis Trigger Algorithm or Technical Trigger Expected rate (kHz) or expected prescale factor to achieve 1 kHz
L = 1032 L = 10 33 L = 2 . 1033
Technical Triggers
minimum bias CASTORetot1 7000 -- --
forward jet production CASTORfwdjet1 100 -- --
forward DY, J/ψ,Υ production CASTORfwdelec2 0.002 -- --
Trigger Algorithms
multi-parton interactions & underlying event studies CASTORetot2 AND Central Jet with ET > threshold -- -- --
inclusive diffraction CASTORrapgap AND ZDCrapgap -- -- --
diffractive jet production CASTORrapgap AND Central Dijet with ET > 40 GeV 0.05 -- --
BFKL studies CASTORfwdjet2 AND Central Dijet with ET > 40 GeV 0.7 -- --
forward DY, J/ψ, Υ production CASTORfwdelec1 AND Central Electron with ET > threshold -- -- --
forward gamma/pizero + jet CASTORfwdgamma AND Central Jet with ET > threshold -- -- --
Trigger Algorithm table for heavy ion running

-- PierreVanMechelen - 14 Jan 2008

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Topic revision: r2 - 2008-01-15 - PierreVanMechelen
 
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