tracking with self-seeded trigger for high … september 2014 niklaus lehmann supervisor: carl h....

04 September 2014

Niklaus Lehmann

Supervisor: Carl H. Haber

Mentor: René Beuchat

Tracking with self-seeded Trigger for High Luminosity LHC

04. Sept. 2014 Self-seeded Trigger - Niklaus Lehmann 2

Content

● Motivation and goals● Project environment● Self-seeded trigger principle● Doublet correlator● Test beam experiment● Conclusion


LHC and ATLAS

LHC

ATLAS detector (current)

Silicon Tracker (current)One of multiple barrels

Module(upgrade prototype)

Inner detector (current)

Stave (upgrade prototype)


Project motivation

● Upgrade of the Large Hadron Collider (LHC) to the High Luminosity LHC planned for mid-2020's

● Increase of luminosity requires upgrade of the ATLAS experiment

● A new trigger and readout system is required to handle the increase of data generated

● Use of the information from the inner detector to create trigger signals → requires fast readout and specific logic to find particle tracks


Silicon strip detectors

1-bit ADC

CF

Preamplifier Pulse shapingAnalog to digital

conversion

Standard readout

∫

Analog front end electronics (ABC130 chip)

Fast readout with cluster finder logic

Threshold

SiO2 insulator

p bulk

p+ backplane

Metal strip

n+ implant

COX

Rbias

Bia

s volt

ag

e

Electric field+++

---

particle

wirebond


ABC130 – Fast Cluster Finder

● New binary readout chip for strip sensors with 256 channels (2 banks of 128 channels)

● Fast Cluster Finder (FCF) for each bank sends information of 2 clusters on every BC cycle

● Designed for fast readout with 640MHz clock● Selects only clusters of 1 or 2 adjacent hits

0 1 126127

Double hit at address 5, Pattern: “10000101”

Undetected hit

Single hit at address 126Pattern: “01111110”

Ignored 3 hit cluster


Self-seeded trigger principle

● New trigger concept to find tracks directly in inner detector

● A track is a series of hit strips on multiple layers● A cluster is 1 or more adjacent hit strips● Fast Cluster Finder logic introduced, on chip, as support

for self-seeded trigger● Correlator logic to match hits on double sided modules

Low PT track High PT track

Double sided stave

Top layer strips

Bottom layer strips


Project goals

● Development and test of correlator logic for a doublet● Complete test system to read data from the

Fast Cluster Finder (FCF)● Implement correlator design for a doublet● Test and verify functionality of correlation logic

● Development of higher level track correlator● Design of correlator to track particles across

two doublets


Correlation methods

● Cluster size method● Limit the size of hit

clusters● Realized in FCF

● Offset method● Limit distance

between top and bottom hit

● Realized in doublet correlator

High PT track Low PT track


Track correlator

● Correlate hits between different barrels● Uses information from doublet correlator● Concept to find straight and curved tracks


Correlator test system

Virtex 6FPGA

Interface board Support board

● Only 20MHz BC and 320MHz FCLK Hybrid


Correlator FPGA design

● Dedicated logic to send commands to ABC130 chips and read values from FCF lines

● MicroBlaze softcore to control the ABC interface and to perform test measurements

ABC130 Interface

MicroBlazeSoftcore

processor

Main controller

Clockmanagement

ABC130commands

Trigger input

Correlator

ABC130Output clocks

toPC

toABC130


Doublet correlator architecture

Row 1(top)

Row 1(bottom)

Row 2(top)

Row 2(bottom)

each line:16 bits @ 320 Mhz

CorrelatorOutputlogicB

uff

er

Buff

er

Stage 1 Stage 2 Stage 3

10

10x1

6b

2 BC cycles(100ns)

1 BC cycles(50ns)

torRowcorrelator

always 10 deserializer

always10x6 row correlators

10x6 cross-row correlators

10x1

2x1

6b

cross-rowcorrelatorcross-rowcorrelatorcross-rowcorrelator

180x19b

180x19b

25 ns per correlation found

To next

stage

torRowcorrelator

10x1

2x1

6b

10x1

6b

10x1

6b

10x1

6b

10x1

6b

10x1

6b

10x1

6b

10x1

6b

10

10

10


Basic correlation logic

● Algorithmic logic to correlate hits

● Basic correlation block calculates distance between top and bottom hit

● 6 possible correlations per row

● 18 correlation blocks per chip pair (2) = 4 (5) = 1

10

14 21

20

(3) = 11

(4) = -6


Correlator data acquisition system

FPGA board

Interfaceboard

Doublet(correlation

demonstrator)

LVD

SSLV

DS

LabVIEWvirtual

instruments

serial C/C++interfacelibrary

ROOT file

Macros forROOT application

with SCTDAQlibraries

Data analysis With ROOT

PC

write

wri

te

read

read


Correlator data acquisition system

● LabVIEW application to control correlator

● Data acquisition and storage for later analysis

● Live plot of found correlations

● Further VIs for characterization measurements


Test beam experiment at SLAC

● Test of correlator demonstrator in a test beam● High energy (~10GeV)● Well controlled beam direction (<0.03°)

● Test performed together with ABC130 single chip board and EUDET telescope

from left to right: Niklaus Lehmann (EPFL / LBL), John Keller (DESY), Haichen Wang (LBL), Jonas Stalder (EIF / LBL), Jake Pasner (UC Santa Cruz), Carl Haber (LBL)

Additional test beam team: S. Diez-Cornell (DESY), A. Blue (University of Glasgow), M. Warren (University College London), B. Gallop (RAL), P. Phillips (RAL), M. Swiatlowski (SLAC)


Correlator demonstrator

● Mechanical support for two modules● One side can be moved horizontally to

introduce an artificial offset – for testing the correlation logic without magnetic field

FrameSensor with hybrid

Support board and anodized Al-plate

HV frame

MicrometerSpring

mobile side

static side

Movement direction


Test beam setup

Doubletdemonstrator

ABC130Single chip

EUDETtelescope

TLUScintillators

Beam machineFPGA

Correlator

HSIOtrig

ger

signal

PC


Beam profile

● Beam spot in the middle of the sensor● Larger number of correlations found on chip

edge● Similar profile as with other experiments


Address bias from FCF

● FCF algorithm favors hits on chip edges

● Simulation shows similar profile as test beam data


Micrometer scan

● Mobile side moved over a distance of 640 µm

● Steps of 80 µm, slightly more than 1 strip (pitch 75 µm)

● Peak moves with micrometer position● Baseline present on all positions, even out of range


Correlation distance vs micrometer position

● Linear relationship within range● Ranges: Row 1 = 3670-4150 Row 2 =3590-4070● Offset of 1 strip between the two rows

(due to wirebonding)


Randomly generated correlations

● Random mask patterns generated in MicroBlaze to create correlations with fix distance

● The created and observed correlations are stored● Similar baseline observed, as in test beam

Test beamSimulation


Randomly generated correlations

Simulation Test beam data

SimulationZoom on y-axis

● Peak larger in simulation than in test beam


Possible improvements

● Correlator● Better rejection of false correlations (close hits

and cross chip hits)● Faster data output

● Data acquisition tools● Integrate together● Increase readout speed● Improve stability of readout

● Implementation of 640MHz fast clock


Acknowledgments

● Lorenzo Pirrami● Basic correlation logic● Base design for ABC130 Interface

● Eric Ropraz and Silvan Duner● Design of Interface, Support board and Hybrid PCBs

● Jonas Stalder● C/C++ Library to create root files from LabVIEW

● Sergio Diez-Cornell● Mechanical design for correlator demonstrator

● Test beam group


Achievements

● ABC130 tested with Fast Cluster Finder● Design for correlation logic was completed● Data acquisition tools developed with LabVIEW● Demonstrator was fabricated● Correlator demonstrator measured in test beam● Test beam data was analyzed● Higher level track correlator concept● Prove of concept for self-seeded trigger


Questions

● Thank you for your attention

● Sources: ● Slide 3: CERN ; ATLAS experiment ; S. Diez-Cornell: “(My highlights of ATLAS Phase II strips

tracker meeting at Valencia”● Slide 6: CERN, “ATLAS Letter of Intent Phase-II Upgrade” ● Slide 7: ATLAS group, “ABC130 specification”● Slide 14: L. Pirrami, “Fast triggering sensor module for the Large Hadron Collider”


Extra slides

● Sources: ● Slide 33: CERN, “ATLAS Letter of Intent Phase-II Upgrade” ; ATLAS Collaboration, “The ATLAS

Experiment at the CERN Large Hadron Collider”

● Slide 34: S. Pirner, “Intelligent Filtering Algorithms for an upgraded Inner Tracker at ATLAS”

● Slide 35: T. Wengler, “The ATLAS Upgrade Programme”

● Slide 41: J. Stalder, “Analysis Tool of High Speed data readout”

● Slide 46: Credit to J. Keller


High Luminosity LHC

● Multiple upgrades planned● Collision energy increased

in 2015● Increase to 5-10 nominal

luminosity in 2024● Inner detector will reach

end of lifetime● Complete replacement of

the inner detector with a new all silicon inner tracker

current inner detector

planned inner detector


Current trigger system

● Uses data from calorimeter and muon spectrometers for L1

● L2 trigger on computer farm using information from complete ATLAS

● Event filter on computer farm as final trigger


Trigger system upgrade

● Trigger used to select only interesting events to be stored for later analysis

● ATLAS uses a multilevel trigger system● Up to L1 in HW, L2 and above on computer

farms● Include data from inner detector in upgrade

for first level trigger● Two approaches:

● Regional readout● Self-seeded trigger


Softcore program

● Control functions for the ABC130 interface● Communicate with serial over USB to

computer● Automatically transmit acquired data from

correlator● Function to find correct phase shift for FCF

input● Average function to perform multiple charge

injection. Used for characterization tests


Wirebonding of sensor

ATLAS07ABC130

3 23 2 1 0 10 32

● Many interesting challenges in electronic packaging and precision mechanics

● Long distance to bonding pads created problems

● One module bonded to far pads (blue)

● Second module bonded to closer pads (red)

● Creates offset of one strip on row 2


Characterization measurements

● First measurements with few channels

10 15 20 25 30 35 40 45 500

0.2

0.4

0.6

0.8

1

1.2

S-Curves

DAC value

Hit

rate

0 1 2 3 4 5 6 7 80

50

100

150

200

250

300

350

400

Response curve

Row1 Ch113

Row1 Ch113 fit

Row1 Ch112

Row1 Ch112 fit

Row1 Ch56

Row1 Ch56 fit

Row1 Ch55

Row1 Ch55 fit

Row2 Ch113

Row2 Ch113 fit

Row2 Ch112

Row2 Ch112 fit

Row2 Ch56

Row2 Ch56 fit

Row2 Ch55

Row2 Ch55 fit

Vt50 [mV]

Inje

cte

d c

ha

rge

[fC

]



● First measurements with few channels

0 1 2 3 4 5 6 7 80

10

20

30

40

50

60

70

Charge [fC]

Ga

in [

mV

/fC

]

0 1 2 3 4 5 6 7 80

200

400

600

800

1000

1200

1400

1600

1800

Row1 Ch113

Row1 Ch112

Row1 Ch56

Row1 Ch55

Row2 Ch113

Row2 Ch112

Row2 Ch56

Row2 Ch55

Charge [fC]

EN

C [

e]



● Left: untrimmed Vt50, gain and input noise for chip 5 to 9 of bottom side

● Top: trimmed Vt50 of same chips


CharacterizationComparison Doublet - Single Chip

Doublet Single chip board


Threshold scan – both sided

● Threshold varied on both sides together● Performed on non-aligned doublet


Threshold scan – single sided

● Threshold varied on only one side – other constant at DAC=40

● µm-position at 3745


Threshold scan – single sided 2




Threshold scan – single sidedonly distance 1 hits




Threshold scan – single sidedonly distance 2 hits




Correlation distance distribution


Matching correlation to telescope

● All telescope and correlator hit combinations plotted for each event

● Matching hits on diagonal line

● Horizontal lines from FCF address distribution

tracking with self-seeded trigger for high … september 2014 niklaus lehmann supervisor: carl h....

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