Silicon Tracker and Space Mission Heritage of DPNC

Xin Wu

Département de Physique Nucléaire et Corpusculaire University of Geneva

ASTROGAM Workshop, 9-10 December, Rome

2 Xin Wu

• Leading institute in many large area silicon trackers

– L3 SMD (DSSD, ~1993)

– AMS-01 (DSSD, ~1996), AMS-02 (DSSD, ~2006)

– ATLAS-SCT (SSSD, ~2005)

– LOFT (SDD, ~2013, pre-study)

– ATLAS-IBL (PIXEL, 2014)

– DAMPE-STK (SSSD, 2014-2015)

• Expertise cover almost all aspects of silicon tracker

– Sensor characterization: probe station, cosmic test stand, CERN test beams

– Front-end hybrid: design of rigid+flex for the analogue readout chain

– Readout electronics: FE control, digitization, data compression, trigger

– Module/ladder: design, assembly (gluing and bonding)

– Light support structure: design, FEA study, production

– Tracker integration: design of gigs and procedure, final integration

– Space qualification: vibration, thermal, thermal-vacuum

– Simulation and commissioning

– Not specialized: front-end ASIC design and sensor fabrication

Long Tradition in Si Trackers

3 Xin Wu

• 100 m2 class 10’000 clean room

• 100 m2 class 100’000 clean room

• Automatic probe station

• Mitutoyo 3D measuring machine for large components

• Wire bonding machine and wire bond pull tester

• Flip chip and bump-bonding machine (June 2015)

• Humidity-controlled thermal chamber

• CNC machines

• Qualified and trained personnel

– Centralized mechanical and electronic groups and clean room crew

• Very broad knowledge base

– Experienced in international collaboration and space projects

DPNC Infrastructure

4 Xin Wu

5 Xin Wu

• Complex ladder structure due to double-sided readout

AMS-02 Ladder

Collaboration with INFN Perugia

6 Xin Wu

AMS-02 Tracker Integration

The DAMPE Detector

7

Plastic Scintillator Detector

Silicon-Tungsten Tracker

BGO Calorimeter

Neutron Detector

Xin Wu

W converter + thick calorimeter (total 32 X0)

+ precise tracking + charge measurement ➠

high energy g-ray, electron and CR telescope

STK

• 12 layers of silicon micro-strip detector mounted on 7 support trays

– Tray: carbon fiber face sheet with Al honeycomb core

• Tungsten plates integrated in trays 2, 3, 4 (from the top)

– Total ~1 X0 for photon conversion

• 8 readout boards (TRB) on 4 sides

8 Xin Wu

Detection area 76 x 76 cm2

DPNC, Perugia, IHEP, Bari

Proposed and led by DPNC

• Weight: ~ 160 Kg

• Total power consumption: ~85W

Si Layer and Ladders CFRP plate Top

Al honeycomb

CFRP frame

Tungsten plates

CFRP plate bottom

Silicon detectors

VA140 (front end chip)

12 layers, 6-x and 6-y

192 TFHs

and Ladders

768 silicon

strip detector

Total ~7m2 Si

1152 ASICs (VA) Xin Wu 9 73728 channels (>500k wire-bonds)!

Ladder Assembly

Xin Wu 10

Wire bonding

• Precise jigs to assemble (align, glue and bond) 4 sensors to a ladder

– 20 µm alignment precision and planarity

Xin Wu 11

12 Xin Wu

First EQM Plane

25 April 2014

13 Xin Wu

One year after the start … 3 July 2014

14 Xin Wu

29 October 2014, PS T9

15 Xin Wu

• DPNC plays leading roles in several major space missions

– With a healthy pipeline of projects in different stages

• AMS-02: in operation since 2011, continue to at least 2020

– General purpose detector with magnetic spectrometer

• POLAR: in construction, launch in 2015

– First measurement of polarization of gamma ray bursts

• DAMPE: in construction, launch in 2015

– Thick calorimeter with tracker/converter: precise measurements of electron/gamma up to 10 TeV and cosmic rays up to 100 TeV

– DM search, CR physics and gamma-ray astronomy

• LOFT

– Front end module assembly. To be resubmitted to M4

• HERD: in design, launch expected ~2020

– Next generation large detector, up to PeV for CR, also DM search and

gamma-ray astronomy

• PANGU: proposal for the ESA-CAS joint small mission

– g-ray telescope with unprecedented angular resolution in sub-GeV range

DPNC Participation in Space Missions

A High Resolution Gamma-Ray Space Telescope Xin Wu1 (European PI) and Jin Chang2* (Chinese PI)

for the PANGU Collaboration 1DPNC, University of Geneva, Switzerland

2Purple Mountain Observatory, CAS, China

PANGU 盤古

Second Workshop on a CAS-ESA Joint Scientific Space Mission 23-24 Sept. 2014, Copenhagen

1°

Limit due to nuclear recoil

arXiv:1311.2059 [astro-ph.IM]

Co

mp

ton

do

mai

n

Angular resolution of pair telescopes

17 X. Wu/J. Chang

PANGU: both tracks in spectrometer

PANGU: both tracks in target

• Geant4 simulation with 150 µm thick single-sided Si detector, 242 µm pitch

⟹ position resolution ~70 µm

• Results are very preliminary

Very limited energy measurement if no tracks in spectrometer • indication of energy with opening

angle and dE/dx in tracker

PANGU Detector Concept

18 X. Wu/J. Chang

• PANGU: dedicated pair telescope with thin tracking layers and no converter

– Push the “thinness” to the limit for best PSF!

• Silicon SSD of 150µm, or ribbon of 3-4 layers of f=250µm fiber

70 cm

30

cm

PANGU ~100 kg

The Target-Tracker

19 X. Wu/J. Chang

• Possible layout

– x-y double layers with 6mm inter-distance, 50 double layers

• Tracking layer with ~0.3% X0 total (requirement)

– Silicon: 2 single sided SSD of 150 µm each

– SciFi: 2 layers of ~0.65 mm each (Polystyrene equivalent), each layer formed by a stack of 3 layers of ø=250 µm fibers, readout by SiPM

• Total tracker active material

– Silicon: ~17kg (silicon density ~2.33 g/cm3)

– Fiber: ~25kg (polystyrene density ~0.9 g/cm3)

• Both need support substrate

– Probably more for Si: biasing, bonding, more fragile

• Baseline: ~50kg for fiber/silicon, support structure, FE electronics

– Plus: 30 kg for magnet, 20 kg for the rest (ACD, DAQ, …)

⟹ total weight ~100 kg

CAS-ESA workshop, 23-24/09/14

20 X. Wu/J. Chang

PSF Comparison with Fermi

PANGU: both tracks in spectrometer

PANGU: both tracks in target

CAS-ESA workshop, 23-24/09/14

Energy [MeV]

10 2103

10

sr]

2A

cce

pta

nce

[cm

210

310

410

Both tracks in target

At least 1 track in spectrometer

Both tracks in spectrometer

Half-sphere downward isotropic incidence

21 X. Wu/J. Chang

Acceptance Compared to Fermi

Fermi

CAS-ESA workshop, 23-24/09/14

Polarisation Measurement

22 X. Wu/J. Chang

• Azimuthal angle distribution in the plane perpendicular to the g direction

– Pg: degree of polarisation; fpol: polarisation direction

– A: Analyzing power, ~0.2 for pair production but kinematic dependent

ds dj = 2ps 0 1+Pg × A×cos(2j -2jpol )( )

• Keys to the measurement

– Azimuthal angular resolution

• transverse track length and multiple scattering

– Intrinsic modulation of the detector!

[Deg]electron

f

-150 -100 -50 0 50 100 150

Fra

ctio

n

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07true reco

true reco

true reco

true reco

Unpolarised input

° = 0qincidence angle

Photon energy (MeV)

50

100

400

600

Detector Intrinsic Modulation

23 CAS-ESA workshop, 23-24/09/14 X. Wu/J. Chang

• Detector intrinsic modulation because of bad f resolution when particle goes in parallel to the strip direction

Intrinsic modulation energy dependent!

More important for higher energy because of smaller

opening angle ⟹ shorter transverse track length

Intrinsic modulation is a function of photon direction Best with normal incidence!

[Deg]lead

f

-150 -100 -50 0 50 100 150

Fra

ctio

n

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07true reco

true reco

true reco

true reco

Unpolarised input

° = 0qincidence angle

Photon energy (MeV)

50

100

400

600

Intrinsic Modulation, Leading Track

24 CAS-ESA workshop, 23-24/09/14 X. Wu/J. Chang

• Electron cannot be identified If no tracks reached spectrometer

– Use leading track

Variable and selection for optimal

PgA should be further studied

[Deg]electron

f

-150 -100 -50 0 50 100 150

Fra

ctio

n

0

0.01

0.02

0.03

0.04

0.05

0.06

unpolarisedA = 0.1gP

A = 0.2gP

A = 0.5gP

Modulated input

° = 0pol

q

° = 0q100 MeV, incidence angle

Input Modulation, Electron

25 CAS-ESA workshop, 23-24/09/14 X. Wu/J. Chang

• Possibility to detect input modulation

– Important to model intrinsic modulation!

– Need reliable simulation code for polarised pair production

Input f distribution modulated with fixed PgA

[Deg]lead

f

-150 -100 -50 0 50 100 150

Fra

ctio

n

0

0.01

0.02

0.03

0.04

0.05

0.06

unpolarisedA = 0.1gP

A = 0.2gP

A = 0.5gP

Modulated input

° = 0pol

q

° = 0q100 MeV, incidence angle

Input Modulation, Leading Track

26 CAS-ESA workshop, 23-24/09/14 X. Wu/J. Chang

Input f distribution modulated with fixed PgA

• Possibility to detect input modulation

– Important to model intrinsic modulation!

– Need reliable simulation code for polarised pair production

Thank you very much for your attention!