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Modification of the near-side jet peak at s NN = 2 . 76 TeV PbPb collisions measured by the ALICE detector Mnika Kfarag CERN ALICE, Utrecht University 6th May 2016 Wigner Theoretical Physics Seminar The current ALICE detector

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SLIDE 1

Modification of the near-side jet peak at √sNN = 2.76 TeV Pb–Pb collisions measured by the ALICE detector

Mónika Kőfaragó

CERN ALICE, Utrecht University

6th May 2016 Wigner Theoretical Physics Seminar

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SLIDE 2

The current ALICE detector Current ITS

Strip (SSD) Drift (SDD) Pixel (SPD) Current ITS has six layers Only two layers equipped with pixel detectors

Mónika Kőfaragó Modification of the near-side jet peak 2 / 11

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SLIDE 3

Upgrade of ALICE in the 2nd LHC long shutdown (2019/2020)

Motivations and strategy: High precision measurements of heavy flavor and charmonia at low p T and low-mass dileptons

cannot be selected by a hardware trigger

Record large minimum bias samples

read out all Pb–Pb collisions at 50 kHz

Integrated luminosity of 10 nb−1 in Pb–Pb (plus pp and p–A data)

factor 100 in statistics compared to LHC Run 1 and 2 (2009 - 2019)

Mónika Kőfaragó Modification of the near-side jet peak 3 / 11

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SLIDE 4

Upgrade of ALICE in the 2nd LHC long shutdown (2019/2020)

Motivations and strategy: High precision measurements of heavy flavor and charmonia at low p T and low-mass dileptons

cannot be selected by a hardware trigger

Record large minimum bias samples

read out all Pb–Pb collisions at 50 kHz

Integrated luminosity of 10 nb−1 in Pb–Pb (plus pp and p–A data)

factor 100 in statistics compared to LHC Run 1 and 2 (2009 - 2019)

Upgrades: New Inner Tracking System (ITS) New Muon Forward Tracker (MFT) Smaller beam pipe Online and offline system Electronics and readout of the Time-Projection Chamber (TPC) Readout electronics of several detectors New Fast Interaction Trigger (FIT)

Mónika Kőfaragó Modification of the near-side jet peak 3 / 11

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SLIDE 5

Design objectives for the upgrade of the ITS

Improve impact parameter resolution by a factor of 3(5) in r-ϕ(z) at p T = 500 MeV/c

First layer closer to interaction point: 39 mm → 23 mm Material budget: ∼ 1.14% X0 → 0.3% X0 for the three innermost layers Pixel size: 50µm × 425µm → 29 µm × 27 µm

CERN-LHCC-2013-24

  • J. Phys. G(41) 087002

Mónika Kőfaragó Modification of the near-side jet peak 4 / 11

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SLIDE 6

Design objectives for the upgrade of the ITS

Improve impact parameter resolution by a factor of 3(5) in r-ϕ(z) at p T = 500 MeV/c

First layer closer to interaction point: 39 mm → 23 mm Material budget: ∼ 1.14% X0 → 0.3% X0 for the three innermost layers Pixel size: 50µm × 425µm → 29 µm × 27 µm

Improve tracking efficiency and p T resolution at low p T

6 layers → 7 layers All layers pixel chips (instead of strip, drift and pixel layers)

CERN-LHCC-2013-24

  • J. Phys. G(41) 087002

Mónika Kőfaragó Modification of the near-side jet peak 4 / 11

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SLIDE 7

Design objectives for the upgrade of the ITS

Improve impact parameter resolution by a factor of 3(5) in r-ϕ(z) at p T = 500 MeV/c

First layer closer to interaction point: 39 mm → 23 mm Material budget: ∼ 1.14% X0 → 0.3% X0 for the three innermost layers Pixel size: 50µm × 425µm → 29 µm × 27 µm

Improve tracking efficiency and p T resolution at low p T

6 layers → 7 layers All layers pixel chips (instead of strip, drift and pixel layers)

Fast readout (present ITS is limited to 1 kHz)

Pb-Pb: up to 100 kHz pp: several 100 kHz

Fast insertion/removal for yearly maintenance

CERN-LHCC-2013-24

  • J. Phys. G(41) 087002

Mónika Kőfaragó Modification of the near-side jet peak 4 / 11

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SLIDE 8

Requirements for the upgrade of the ITS

Beam pipe Outer layers Middle layers Inner layers

7 layers of pixel sensors (r = 23 − 400 mm) 10 m2 of silicon with 12.5 Gpixels |η| < 1.22 for tracks from 90% of the most luminous region

Mónika Kőfaragó Modification of the near-side jet peak 5 / 11

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SLIDE 9

Requirements for the upgrade of the ITS

Beam pipe Outer layers Middle layers Inner layers

7 layers of pixel sensors (r = 23 − 400 mm) 10 m2 of silicon with 12.5 Gpixels |η| < 1.22 for tracks from 90% of the most luminous region

Parameter Inner barrel Outer barrel Silicon thickness 50 µm 100 µm Spatial resolution 5 µm 10 µm Power density < 300 mW/cm2 < 100 mW/cm2 Event resolution < 30µs Detection efficiency > 99% Fake hit rate < 10−6 per event per pixel Average track density 15 - 35 cm−2 0.1 - 1 cm−2 TID radiation * 2700 krad 100 krad NIEL radiation * 1.7 × 1013 1 MeV neq/cm2 1012 1 MeV neq/cm2 * Including a safety factor of 10

Mónika Kőfaragó Modification of the near-side jet peak 5 / 11

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SLIDE 10

Technology choice

Monolithic Active Pixel Sensors using TowerJazz 0.18 µm CMOS imaging process High-resistivity (> 1kΩ cm) epitaxial layer on p-type substrate Quadruple well process: deep PWELL shields NWELL of PMOS transistors, allowing for full CMOS circuitry within active area Moderate reverse substrate biasing is possible, resulting in larger depletion volume around NWELL collection diode

e e e e h h h h

PWELL PWELL NWELL DEEP PWELL NWELL DIODE NMOS TRANSISTOR PMOS TRANSISTOR Epitaxial Layer P- Substrate P++

Diffusion Drift

Mónika Kőfaragó Modification of the near-side jet peak 6 / 11

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SLIDE 11

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 12

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 13

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Two types of reset mechanisms

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 14

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Input node where charge is collected

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 15

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Charge is transfered from CS to the output node

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 16

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Pixel is registered as hit

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 17

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Two main parameters to change the charge threshold

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 18

Specification of the pALPIDE-1

First prototype with final size (15 mm × 30 mm) 512 × 1024 pixels Pixels are 28 µm × 28 µm Digital readout with priority encoder Four sectors with different pixel geometries and reset mechanisms 30 mm 15 mm

1 2 3

VRESET PWELL IBIAS source curfeed VCASP AVDD AVSS VCASN ITHR IDB M0b D1 M1 M2 M3 Cs Cf M4 M5 IRESET pix_in pix_out PIX_OUT_B VPULSE Cinj 230 aF VAUX D0 Diode Reset PMOS Reset AVSS M0a

Injection capacitance for measuring threshold

Mónika Kőfaragó Modification of the near-side jet peak 7 / 11

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SLIDE 19

Characterization in test beam

DAQ board Carrier card pALPIDE-1

Mónika Kőfaragó Modification of the near-side jet peak 8 / 11

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SLIDE 20

Characterization in test beam

DAQ board Carrier card pALPIDE-1

Test beam Tracking is done by a stack of 7 layers of pALPIDE-1 Readout and analysis is done using the EUDAQ/EUTelescope framework * Measurement of detection efficiency and spatial resolution

*https://eutelescope.web.cern.ch

B e a m

7 p A L P I D E

  • 1

7 D A Q b

  • a

r d s

Device Under Test Tracking planes

Track

Mónika Kőfaragó Modification of the near-side jet peak 8 / 11

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SLIDE 21

Characterization results

Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

Efficiency (%)

97 97.5 98 98.5 99 99.5 100

Efficiency is well above 99%

Mónika Kőfaragó Modification of the near-side jet peak 9 / 11

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SLIDE 22

Characterization results

Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

Efficiency (%)

97 97.5 98 98.5 99 99.5 100

Noise occupancy per event per pixel

  • 8

10

  • 7

10

  • 6

10

  • 5

10

  • 4

10

  • 3

10

20 noisiest pixels masked

Efficiency is well above 99% Noise occupancy is below 10−6 hits/event/pixel above ∼ 140 electrons

Mónika Kőfaragó Modification of the near-side jet peak 9 / 11

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SLIDE 23

Characterization results

Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

Efficiency (%)

97 97.5 98 98.5 99 99.5 100

Noise occupancy per event per pixel

  • 8

10

  • 7

10

  • 6

10

  • 5

10

  • 4

10

  • 3

10

20 noisiest pixels masked Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

m) µ Resolution (

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6

2.26 µm tracking error is assumed for the resolution

Efficiency is well above 99% Noise occupancy is below 10−6 hits/event/pixel above ∼ 140 electrons Resolution is below 5 µm with a large operational margin

Mónika Kőfaragó Modification of the near-side jet peak 9 / 11

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SLIDE 24

Characterization results

Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

Efficiency (%)

97 97.5 98 98.5 99 99.5 100

Noise occupancy per event per pixel

  • 8

10

  • 7

10

  • 6

10

  • 5

10

  • 4

10

  • 3

10

20 noisiest pixels masked Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

m) µ Resolution (

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6

Average cluster size (pixels)

0.5 1 1.5 2 2.5 3 3.5

2.26 µm tracking error is assumed for the resolution

Efficiency is well above 99% Noise occupancy is below 10−6 hits/event/pixel above ∼ 140 electrons Resolution is below 5 µm with a large operational margin Average cluster size is above two pixels on average

Mónika Kőfaragó Modification of the near-side jet peak 9 / 11

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SLIDE 25

Characterization results

Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

Efficiency (%)

97 97.5 98 98.5 99 99.5 100

Noise occupancy per event per pixel

  • 8

10

  • 7

10

  • 6

10

  • 5

10

  • 4

10

  • 3

10 Noise Efficiency Non irradiated

2

/ cm

eq

1 MeV n

13

10

20 noisiest pixels masked Threshold (electrons)

80 100 120 140 160 180 200 220 240 260

m) µ Resolution (

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6

Average cluster size (pixels)

0.5 1 1.5 2 2.5 3 3.5

Cluster size Resolution Non irradiated

2

/ cm

eq

1 MeV n

13

10 2.26 µm tracking error is assumed for the resolution

Efficiency is well above 99% Noise occupancy is below 10−6 hits/event/pixel above ∼ 140 electrons Resolution is below 5 µm with a large operational margin Average cluster size is above two pixels on average After irradiation:

Efficiency and resolution does not change Cluster size slightly smaller Noise occupancy slightly higher

Mónika Kőfaragó Modification of the near-side jet peak 9 / 11

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SLIDE 26

Characterization results

Cluster size distribution as function of impinging point of tracks within pixel

X (mm) 0.01 0.02 Y (mm) 0.01 0.02 Average cluster size (pixels) 1.4 1.6 1.8 2 2.2 2.4

Average cluster size is

largest at the corner of pixels smallest at the center of pixels

Mónika Kőfaragó Modification of the near-side jet peak 10 / 11

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SLIDE 27

Characterization results

Cluster size distribution as function of impinging point of tracks within pixel

X (mm) 0.01 0.02 Y (mm) 0.01 0.02 Average cluster size (pixels) 1.4 1.6 1.8 2 2.2 2.4

1 2 3

Distance along cross section (mm) 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 Average cluster size (pixels) 1.5 2 2.5 3 3.5

= 70 DAC units

thr

I = 51 DAC units

thr

I = 40 DAC units

thr

I = 30 DAC units

thr

I = 20 DAC units

thr

I

1 2 3 1

Average cluster size is larger at low Ithr Average cluster size changes less within a pixel at high Ithr

Mónika Kőfaragó Modification of the near-side jet peak 10 / 11

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SLIDE 28

Summary and outlook

The current ITS will be replaced in 2019–2020 7 layers of monolithic pixel sensors will be used Results from first full-scale prototype shown:

All requirements are fulfilled Large operational margin Satisfactory results also after irradiation with 1013 1 MeV neq/cm2

Changes in newer prototypes:

All features needed for module integration added Analog front-end optimization Multi-event buffers added Noise occupancy lowered by orders of magnitude

Final chip is submitted soon

Thank you for your attention!

Mónika Kőfaragó Modification of the near-side jet peak 11 / 11