TDR Updates - Algorithms
This page provides information on changes to the calorimeter trigger design made after
submission of the TDR. Information on changes to TDR
Technologies and External Systems is also available.
| TDR- Page 31 |
Updated Version |
| 16 sets of thresholds are organised as 8 for em and
8 for tau triggers. |
16 sets of thresholds. The first 8 are for em
triggers only. The second 8 can be programmed to define em or tau triggers, giving
the flexibility to run more em (and less tau) triggers if needed. |
| Presented: Level-1 Collaboration Meeting at CERN
4-Sep-1998 (A Watson), Level-1 UK at RAL 23-Nov-1998 (A Watson), Level-1 Collaboration
Meeting Heidelberg 30-Nov-1998 (P Watkins) and Birmingham 6 March 1998 (A Watson). |
| Status: Agreed |
| TDR- Page 30 |
Updated Version |
| All 16 towers in the 4*4 tower region
are summed and compared with a single Hadronic isolation threshold. |
An inner 2*2 region (4 towers) and an
outer ring of 12 towers are summed separately and compared to two separate thresholds. The
threshold conditions must both be satisfied to produce a trigger. The change offers
increased flexibility and may marginally improve rejection. |
| Presented: Level-1 UK at RAL 23-Nov-1998 (A Watson),
Level-1 Collaboration Meeting at Heidelberg 30-Nov-1998 ( P Watkins) and Birmingham 6
March 1998 (A Watson). |
| Status: Approved by T/DAQ Steering
Group 22/7/99. No adverse effects on signal efficiency seen in any situation simulated,
and possibly slight benefits. Atlas note in preparation. |
| TDR- Pages 36-40, 49-50 |
Updated Version |
| The position is defined by the highest of the
overlapping 2*2 area sums which satisfy the threshold criteria. The sum is over the em
calorimetry only for em triggers and over em and hadronic calorimetry for tau triggers. |
The position is defined by the highest 2*2 area sum
satisfying the threshold criteria. For both em and tau triggers, the sum is over em and
hadronic calorimetry. If the em trigger fires, isolation ensures a very small energy
deposit in the hadronic layer. The common algorithm simplifies implementation and
marginally improves jet rejection (when used with 2-region hadronic isolation), and also
slightly simplifies the RoI format. |
| Presented: Level-1 UK at RAL 23-Nov-1998 (A Watson),
Level-1 Collaboration Meeting at Heidelberg 30-Nov-1998 (P Watkins) and Birmingham 6 March
1998 (A Watson). |
| Status: Approved by T/DAQ
Steering Group 22/7/99. No adverse effects on signal efficiency seen in any situation
simulated, and possibly slight benefits. Atlas note in preparation. |
|
The ATLAS Level-1 Calorimeter Trigger