nikos varelas university of illinois at chicago l2cal group at uic: mark adams bob hirosky

Nikos Varelas

University of Illinois at Chicago

L2Cal Group at UIC:Mark Adams

Bob Hirosky

Rob Martin

Nikos Varelas

Marc Buehler (graduate student)

James Heinmiller (undergraduate)

Mike Klawitter (part time engineer)

1 2/6/99 L2 Review NV/UIC

2/6/99 L2 Review 2NV/UIC

L2Cal Crate and I/O

Status of L2Cal Algorithms:

Jets

Electrons

Missing ET

Timing of Algorithms

Summary


• From Calorimeter via FIC/MBT: 10 input cables with 304 Bytes/cable – Header

– L1 Seed Tower Bit Masks for EM and Total

– L1 Tower ET data for EM and Total

• From SCL via MBT:– L1 accept (3 Bytes)

– L1 Qualifiers (2 Bytes)• L2Jet Needed

• L2Em Needed

• L2Etmiss Needed

• 3 Spare Bits

• Unbiased Sample

• Forced Write

• Collect Status

– L2Global accepts


• To L3– For normal events send the L2Global output

– For UBS or Forced Write events the full L1 input and L2Cal output will be sent

• To L2Global– About 136 Bytes/event (including headers)

– Will be fine tuned when algorithms are finalized based on input from physics/Id groups

• Each worker will preface its data with a 12Byte header– Header will include information about the

processing status (i.e., format errors, timeouts etc) of the event

• Each worker will complete transmission with a 4 Byte trailer


All L2Cal algorithms will use a low-threshold reference set of L1 0.2x0.2 trigger towers as input for clustering.

L1 EM ET - Rounded in 0.25 GeV stepsL1 Tot ET - Sum of EM and HAD truncated in

0.5 GeV steps

L2Cal ProcessorsL2Cal Processors

jet

electron

neutrinoWhat are the efficiencies of these algorithms?

Can we reduce the trigger rate w/o significant cost

in efficiency?

Can we do all these stuff in less than 100 s???


• The algorithm:

• Event Samples used in simulations:– Data: WJJ triggers from Run 1C Global

Runs with Lum = 17E30– MC: UPG GEANT inclusive jet events w/

generated thresholds: (2,5,10,20,40,80 GeV) overlapped with: (1,3,5,7) additional MB

interactions (not overlapped with noise)

Start w/ list of jet seed towers from L1• For each seed tower, cluster ET of the surrounding 5x5 (or 3x3)

tower array • Add to Jet list all clusters whose ET sum exceeds a min threshold• ET order the Jet list (descending order) • Eliminate Jets failing overlap restriction

If ET(A) > ET(C) ; keep A,BIf ET(C) > ET(A) ; keep C,B


WJJ DataTower Seed Distributions

Threshold RMS

1.0 GeV 40 20

1.5 GeV 17 7

2.0 GeV 9 4

For a high-ET (>350GeV) jet data sample: = 20, RMS= 6 for L1(1,2)


WJJ DataL2 Jet Distributions


Measured w/ MC - UPG Geant sample

Pjet and Cal Jet matching methods:

1) Projection Method

2) Matching Method(run L2Jet algorithm)

PJet

calorimeter

Project PJet axis intocalorimeter.Does corresponding seed/cluster ET passimposed cuts?

PJet

calorimeter

R<0.5?

Compare L2Jets to PJetsLook for matches


Reference algorithm L1(1,2) L2(1,10)

Eff

s. f

or s

eed

/clu

ster

cu

ts a

nd

Alg

orit

hm

(see

d c

ut,

clu

ster

cu

t)L2Jet Efficiency for seeds/clusters

Central jets


L2Jet Rate Estimates

11

1

(weight) x ) samplein events(#

(weight) x ) thresholdpassing events(#Rate

• Method:– First weight MC events appropriately

1) use JETRAD to bridge all PJet Cross Section to central inclusive jet CS in data

2) estimate total MC event cross section for PJet ET>5 GeV; ~ 1/11 Min Bias cross section

– Calculate trigger rate as ~ fraction of MB events passing imposed threshold(s)

• Plot L2Jet Efficiency vs Rate for 20 and 100 GeV PJets.– Compare L2 3x3 jet algorithm to 5x5 version

– Measure Eff. vs Rate w/ and w/o L2 clustering

– Examine the effects of 0.5 GeV truncation to trigger-tower ETs


3 = 3x3 algorithm 5 = 5x5 algorithm

• ~ factor of 3 rate reduction w/ 20% eff. cost• no strong cluster size preference• need to tune the MC further so we can study/improve the algorithm for low-ET jets

L1(1,1.5)

L1(1,2)

L2 thresholds (1,10)(1,8)(1,6)(1,4)(none)

3x3

5x5

L1 only

Eff. vs Rate at 20 GeV


3 = 3x3 algorithm 5 = 5x5 algorithm

Eff. vs Rate at 100 GeV

L1(1,7)

L1(1,9)

• order of magnitude rate reduction easily attainable at L2 w/o loss in efficiency• no strong cluster size preference

L1 only

L2 thresholds (1,60)(1,50)(1,40)(1,30)(none)


Effects of L1 Total-ET Truncation for 20 GeV Jets

L2 (1,4)

L2 (1,6)

L2 (1,8)

L2 (1,10)

L2 (1,12)

L2 (1,15)

L1 (1,2)

the effect of L1 energy truncation can be accommodatedat L2 by choosing lower jet thresholds

0.25 GeV rounding

w/ 0.5 GeV truncation


An Example at Lum=1E32

Level-0

45 mb x 1E32 = 4.5 MHz

L1(1,9)

6.7 KHz

<L2(1,30)>

130 Hz

L3

L1(1,12)

Eff at 100 GeV

~ 96%

~ 92%

1800 Hzfor same Eff


• The algorithm:

• Event Samples used in simulations:– Single electrons uniformly distributed in in the forward

region: 1.9<||<2.3– ISAJET dijet events with various thresholds starting at

2 GeV

Events were processed through UPG_GEANT with two (onaverage) additional interactions (not overlapped with noise)

Start w/ list of EM seed towers from L1• For each seed tower, determine nearest neighbor w/ the largest ET • Calculate the following summed ET : quantities:

1) ET(EM) of seed tower + largest neighbor 2) ET(Total) of seed tower + largest neighbor 3) sum ET(Total) of 3x3 trigger towers centered on seed tower

• Order surviving candidates in descending ET(EM)

Apply cuts on ET(EM), EM fraction, andIsolation


• L1 Cuts:– FPS: 0.3 MIPs (upstream)

5 MIPs (downstream)

U view matching

V view matching

– CAL: EM trigger tower above threshold

– Match FPS with CAL L1 Tower in Quadrant

• L2 Cuts:– FPS: Require downstream U and V view

matching convert to , in 0.2 x 0.2 bins

– CAL: Find EM cluster using NN algorithm. Apply EM fraction and Isolation cuts.

– Match FPS track to EM cluster within x = 0.3 x 0.3

• No rounding/truncation applied to L1 tower energies

Courtesy Mrinmoy Bhattacharjee


Eff. vs Background Rate at 18 GeV

Forward electrons

L2 thresholds (1,15)(1,12)(1,10)(none)

L1 (1,7)

L1 (1,7)

preliminary



Forward electrons


L1 (1,10)

L1 (1,10)

preliminary



Forward electrons


L1 (1,7)

L1 (1,7)

preliminary

order of magnitude rate reduction attainable at L2 w/ small cost in efficiency

w/ FPS match



Forward electrons


preliminary

L1 (1,10)

L1 (1,10)

order of magnitude rate reduction attainable at L2 w/ small cost in efficiency

w/ FPS match


• Candidates will be sorted in descending ET order

• Information per candidate– eta (1 Byte)

– phi (1 Byte)

– ET (2 Bytes)

– eta center (1 Byte)

– phi center (1 Byte)

– eta leading TT (1 Byte)

– phi leading TT (1 Byte)

– Spare (4 Bytes)

• Total 12 Bytes/object


• Candidates will be sorted in descending ET order

• Information per candidate– eta (1 Byte)

– phi (1 Byte)

– ET (2 Bytes)

– EM fraction (1 Byte)

– Isolation Fraction (1 Byte)

– eta leading TT (1 Byte)

– phi leading TT (1 Byte)

– eta other TT (1 Byte)

– phi other TT (1 Byte)

– Spare (2 Bytes)

• Total 12 Bytes/object


• Need input from physics groups

• Information per event– Missing ETX (2 Bytes)

– Missing ETY (2 Bytes)

– Scalar ET (2 Bytes)

– Spare (10 Bytes)

• Total 16 Bytes/event


• The algorithm:

• Possible Enhancements:– Calculate Scalar ET using the same cuts as for

Vector ET

– Calculate ET for more than one set of Tower cuts

– Calculate ET using different threshold for each Tower

Loops over all towers within prescribed range, calculating the vector ET sum of all towers with ET > Min_Tow_ET. It returns the X and Y components of the Missing ET.


• Code:– written in C

– compiled with C or C++ compiler on DEC Alpha workstation running UNIX (timing results

roughly the same)

– Executable down-loaded and run on UIC PC164 evaluation board containing DEC 21164 Alpha processor with 500MHz clock

• Event Sample:– MC Dijet data generated with ISAJET

– Data block Structure as planned for hardware• 10 “cable blocks” containing:

* EM Tower Seed Mask

* Total Tower Seed Mask

* EM Tower ET data

* Total Tower ET data


Jet proc time vs # seeds

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30

# Level 1 seeds

Tim

e (u

s)

Time (s) ~ 2.5 + 1.12 x (# seeds)

Average seed range


Time (s) ~ 2 + 2.3 x (# seeds)


MET Mean Processing time

30

31

32

33

34

35

36

37

38

39

40

0 200 400 600 800 1000 1200 1400

Mean # Tow ers

Mea

n T

ime

(us)

The average time for 0.5 GeV Tower ET threshold is ~ 33 s

All Towers abovethreshold


• We have a fully designed L2Cal Preprocessor system which has sufficient CPU power to execute reasonable L2 algorithms with < few % deadtime– if more power needed, can add up to two

Workers for parallel processing

• We have working versions of Jets/Electron/Missing ET algorithms which offer acceptable rate reduction

• The data movement architecture is complete and the monitoring path has been established (see previous talks)

• We request TDR approval

nikos varelas university of illinois at chicago l2cal group at uic: mark adams bob hirosky

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