Triggering with CASTOR
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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