1) Draft specification of the Run2B L1 Calorimeter Trigger
Resource Programming by COOR
The current set of specifications is described in the following web page.
http://www.pa.msu.edu/hep/d0/ftp/run2b/l1cal/tcc/coor/coor_to_l1caltcc_message_syntax.txt
The limitations of the current set of specifications are described
at point 3) below.
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2) Messages COOR will send to L1Cal2B TCC available today (4/24/06):
(E-mail from Scott Snyder 10/12/05)
The set of specification in 1) was used as a base for developing
the XML syntax generated by COOR and sent to the trigger control
computer. This syntax is described in the following paragraphs.
Proposed changes to this syntax, considering the proposed changes to
the COOR resources programming, are described in point 3) below.
The X's below represent required attributes, the O's optional ones.
In addition to the attributes below, all terms take the optional
attributes `number', to explicitly specify which term to allocate,
`ownmode', to specify the coor ownership mode, and `require',
to specify the require/veto sense of the term in a term list.
Some notes. Coor parameterizes reference sets in terms of a threshold
and a maximum eta (defaulting to the full calorimeter). Outside the specified
eta range, the refset threshold will be set to the maximum. Due to the
sorting requirement, not all combinations of threshold/maxeta will
be possible. However, if the maxeta specified matches the hardwired
cutoff for a `central' term, that `central' term will be used,
with the refset itself including the full eta coverage.
The rsnumber attribute can be used to force allocation of a specific
reference set; otherwise, coor will choose.
For l1iso_em, the emfraction and isolation ratios may be specified.
If defaulted, they are taken as `0' (no requirement).
These settings must be the same for all l1iso_em terms used
at any one time.
l1aco_jet has two associated reference sets; the second (veto) is specified
via the attributes ending in `_v'. If they are all defaulted, then
the two reference sets used will be identical. (This is the only
configuration that's allowed by the current firmware, anyway.)
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3) Limitations of the current calorimeter trigger resource
programming specifications.
a) The current document specifies at III.1.g the procedure for
defining the reference sets which are not allocated by COOR.
However this procedure has a limitations: both for the EM and
for the Jet triggers reference set 0 will not be downloaded by
from the triggerlist according to the current specifications.
COOR will download a reference set only if it is used in a trigger,
but reference set 0 cannot be used in a trigger, since the corresponding
object count is not transferred from the TAB to the GAB.
The current document specifies at III.1.g that the lowest
reference sets which are not assigned via a trigger
requirement will have the threshold set to the same value
as the lowest threshold used for a trigger.
The current plan is to use the 0-th reference threshold
to create the mask of L1 objects sent to the L2 trigger.
This threshold may have other uses as well (it could be
used as the threshold when finding EM objects which pass
the isolation/EMfraction cuts, it could be used as the
threshold veto for the acoplanar jets trigger, it could
be used as the threshold applied to the jet objects
used for the calculation of the tau ratios)The definition of the value of the 0-th reference threshold
does not require any change in the TCC-TAB communication.
However it does require a change in the message sent from
COOR to the TCC and a corresponding change in the XML syntax.
Proposal: change the syntax of the EM, jet and tau triggers from
to the following:
where the lowthres parameter specifies the lowest ET threshold
(associated to reference set 0). COOR should check that:
* all EM triggers share the same value of the "lowthres" parameter
* all the jet and tau triggers share the same value of the "lowthres" parameter
* the only allowed values of the "rsnumber" parameter are 1-6
* all "thresh" parameter downloaded by the user are greater
or equal to the corresponding "lowthres" parameter
In section III.1.g of the COOR resources programming document the paragraph:
- If the lowest Reference Set allocated by COOR is #N, with N!=0, TCC
will program all Reference Set #M, with 0 <= M < N to the same threshold
as the one COOR defined for Reference Set #N.
is modified as
- If the lowest Reference Set allocated by COOR is #N, with N>0, TCC
will program all Reference Set #M, with 0 < M < N to the same threshold
as the one COOR defined for Reference Set #N.
POSSIBLE SIMPLIFICATION:
------------------------
Reference thresholds 0 both for EM and jets are set in the TCC configuration
files to 3 GeV for the EM and 5 GeV for the Jet triggers. No modifications to
the XML and COOR download are needed.
b) The EM isolation ratio and the EM/HD fraction ratio both require one
additional parameter to be transferred from TCC to the TAB. This parameter
contains the minimal ET of an EM object found by the TAB to be considered
when setting the EM isolation and the EM/HD fraction ratio flags.
Proposal: extend the messages programming TCC from
"L1CAL_Ref_Set EM_Isolation TT_Eta(-20:20) TT_Phi(1:32) Ratio "
"L1CAL_Ref_Set EM_HD_Fraction TT_Eta(-20:20) TT_Phi(1:32) Ratio "
to
"L1CAL_Ref_Set EM_Isolation TT_Eta(-20:20) TT_Phi(1:32) Ratio EM_Et_Ref_Set "
"L1CAL_Ref_Set EM_HD_Fraction TT_Eta(-20:20) TT_Phi(1:32) Ratio EM_Et_Ref_Set "
where RS_Number is one of the available reference sets (0 to 6) already
downloaded.
This requires a corresponding modification of the XML syntax from
to
where "objthres" is a new parameter, which can assume a value
between "lowthres" and "thresh".
COOR should check that:
* all EM_iso triggers share the same value of the "objthres" parameter
* "objthres" corresponds to one of the 7 reference thresholds being downloaded
POSSIBLE SIMPLIFICATION
-----------------------
At the cost of some flexibility (which current studies indicate is NOT needed)
we could decide to use "lowthres" as "objthres" and have a single parameter
transferred from COOR to TCC. We could do this without modifying the message
sent from COOR to TCC and have the TCC code send the reference set 0 to the
TABs as the reference threshold used for selecting the EM objects which are
used for setting the EM isolation and EM/HD fraction ratio flags.
c) New requirement: minimum ET in a trigger tower for inclusion in the missing ET
sum.
The new TAB firmware contains a new downloadable parameter which sets a threshold
in ADC counts for the inclusion of a trigger tower in the sums used for the
calculation of the missing ET and total ET. TCC must transfer this parameter
to each TAB (a single parameter is used both for the EM and HAD towers).
Proposal: add the following message from COOR to TCC
"L1CAL_to_L1FW Global_Sums minTower_ET "
to the two already existing messages
"L1CAL_to_L1FW Missing_Et_Term Energy_Threshold "
"L1CAL_to_L1FW Total_Et_Term Energy_Threshold "
where the minTower_ET is an energy in GeV (steps of 250 MeV, this gets
transformed into an 8 bit number which TCC sends to the TAB - beware of
pedestals !!!!)
This also requires changing the corresponding XML messages from
where the optional parameter mintowerET is set to the default value
of -2 GeV in case it is not specified in the triggerlist (this
corresponds to 0 ADC counts).
A single value of the minTower_ET parameter is allowed for the
CSWTET and CSWMET triggers.
d) New requirement: tau triggers.
The new TAB/GAB firmware will contain a new version of the tau triggers
which requires a new definition of the messages being sent from COOR to
TCC. The basic features of the new tau triggers are the following:
* the ET reference sets used for taus are the same as the ones used
for jets (i.e. there are only 7 transverse energy thresholds in total for
jets plus taus)
* in addition to the ET threshold the tau trigger also has the
possibility of applying a cut on the ratio of the energy in
a 2x2 region and the energy in a 4x4 region (this ratio is
called tau ratio in the following).
* each TAB sends to the GAB the count of jets passing the ET
cuts and a separate count of objects passing the tau ratio
reference cuts
* only jet objects having an energy above a given threshold
are used for calculating the ratio cuts.
Therefore the TCC has to download the following parameters to each TAB:
* the 7 ET thresholds (used both for jets and taus)
* the 7 tau ratio cut values (use a number between 0 and 1 encoded
in 8 bits)
* the number of the reference set used for selecting the
objects which are used for the calculation of the tau ratio.
COOR will NOT send messages of the type:
"L1CAL_Ref_Set Tau_Et_Ref_Set TT_Eta(-20:20) TT_Phi(1:32) Energy_Threshold "
Therefore the proposed syntax for the COOR download of the tau triggers
is the following (this is the information needed to properly configure the TABs):
"L1CAL_Ref_Set Tau_Ratio_Ref_Set TT_Eta(-20:20) TT_Phi(1:32) Ratio_Threshold Jet_Et_Ref_Set "
where Jet_Et_Ref_Set is one of the Jet ET reference sets
(Since the reference set Tau_Ratio_Ref_Set 0 will never be used in a trigger we can either ignore it or
define it as 0 all the time).
(Apply to the Tau_Ratio_Ref_Set the same rules used for the EM_Et_Ref_Set and Jet_Et_Ref_Set)
The tau triggers will be formed in the GAB by requiring a phi-coincidence between
the jet threshold and the ratio threshold. No change is needed in the message sent
from COOR to the TCC:
"L1CAL_to_L1FW Tau_All_Term Use_Ref_Set Count_Threshold Tau_Ratio "
In addition to trigger terms over the entire calorimeter rapidity range we propose to
add also trigger restricted to the central region. Therefore TCC will deal also with
messages of the type:
"L1CAL_to_L1FW Tau_Central_Term Use_Ref_Set Count_Threshold Tau_Ratio "
These changes in the messages sent from the COOR to the TCC require the following
changes in the XML syntax. The current message:
needs to be expanded to
where "ratio" is a parameter (0-1, using 8 bits) specifying the tau ratio cut,
"rsratio" is an optional parameter specifying the ratio reference set.
"objthres" is the minimal ET used for calculating the tau ratio (corresponds to one
of the jet thresholds).
NB: The tau ET thresholds should be counted together with the jet ET thresholds
when counting the reference thresholds for jets.
POSSIBLE SIMPLIFICATION:
------------------------
Specify the value of rsratio (or Jet_Et_Ref_Set) in the TCC configuration
file (use reference set 1 or 0, most likely 1).
Specify the values of the tau ratios in the TCC configuration file and
use only the tau ratio reference set number in the COOR download.
e) New requirement. Flags to turn on/off the use of the ICR towers in the
EM/Jet sums and in the missing ET/total ET sums (2 flags).
We have two (or three ????) new downloadable parameters which control the
inclusion of the ICR towers in the formation of the EM/Jet and missing ET/total ET
sums inside the TABs. This requires either new messages of the type:
"L1CAL_Ref_Set EM_Use_ICR <0/1>"
"L1CAL_Ref_Set Jet_Use_ICR <0/1>"
"L1CAL_Ref_Set Global`_Use_ICR <0/1>"
or the addition of a Use_ICR flag to all the following mesages:
"L1CAL_Ref_Set EM_Et_Ref_Set ......."
"L1CAL_Ref_Set Jet_Et_Ref_Set ......."
"L1CAL_to_L1FW Global_Sums ......."
This also requires adding the corresponding flag to all XML messages:
POSSIBLE SIMPLIFICATION
-----------------------
Set this flag in the TCC configuration files.
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4) Things which are still missing:
* configuration of 2 new acoplanarity triggers (ACOKILL and ACOMONO)
* assignment of trigger framework bits (need to count again bits and
reassign map of bits send from GAB to trigger framework, surely
need more tau terms).