The Mu3e Experiment 2/

Testbeam Measurements with MuPix Sensors

Moritz Kiehn for the Mu3e Collaboration

Physikalisches Institut, Universität Heidelberg

PI Palaver, Heidelberg, 30. April 2014

The Mu3e Experiment 2/

e

e

e

• Precision experiment

• Search forµ⁺ → e⁺e⁻e⁺

• Sensitivity<1 in 10¹⁶ decays

• Standard Model1 in 10⁵⁰ Importance ?

• Indirect new physics search

• High sensitivity

Signals and Backgrounds 3/

Signal

e⁺

e⁺ e^-

Backgrounds Internal Conversion

e^- e⁺

e^{+ ν}

ν

Combinatorial

e⁺

e⁺ e^-

• Common vertex

• P

~ p_i =0

• p <53 MeV

• Common vertex

• P

~ p_i 6=0

• In-time

• No common vertex

• Out-of-time Requires σ_p<0.5 MeV

σ_t <20 ns

Multiple Scattering 4/

Ω MS

θ

B

θ

=

p x /X

Example

• p =35 MeV

• 200 µm Si

• ΩR =5 cm

• ∆y ≈1 mm

The Mu3e Experiment 5/

Target Inner pixel layers

Scintillating f bres

Outer pixel layers Recurl pixel layers

Scintillator tiles μ Beam

Environment

• >10⁹ µ⁺ Decays/s

• Electrons p<53 MeV

• Multiple scattering dominates

Pixel Sensor Requirements

• Fast <20 ns

• Thin<1 ‰X₀

• Pixel 80×80 µm²

Ultra-Lightweight Mechanics 6/

• 50 µm Silicon sensor

• 25 µm Kapton flexprint

• 50 µm Kapton support frame

→ <1 ‰ Radiation length

Silicon Pixel Sensors 7/

Hybrid

Sensor 250 μ Read m

out c hip 180 μm

Pixel

Pixel electronics Connection via solder bump

Global logic and data driver

Monolithic Active Pixel Sensor

• HV ∼700 V

• Sensor thickness∼250 µm

• Extra material

• Complex and expensive

• HV ∼70 V (HV-MAPS)

• Thin active zone<20 µm

• Cheap, commercial process

Silicon Pixel Sensors 7/

Hybrid

Sensor 250 μ Read m

out c hip 180 μm

Pixel

Pixel electronics Connection via solder bump

Global logic and data driver

Monolithic Active Pixel Sensor

Monolithic Sensor 50 μm

Pixel

Pixel electronics

Global logic and data driver On-chip interconnect

• HV ∼700 V

• Sensor thickness∼250 µm

• Extra material

• Complex and expensive

• HV ∼70 V (HV-MAPS)

• Thin active zone<20 µm

• Cheap, commercial process

MuPix4 HV-MAPS Prototype 8/

32 Columns / 2.944 mm

40 Rows / 3.2 mm

I. Peric, P. Fischer et al.

NIMA 582(2007)876

• 92×80 µm² pixel size

• Global threshold

• Zero-suppressed digital readout

• Timestamps

• Incorrect address every 2^nd double row

DESY Testbeam 9/

z x Beam

Beam Telescope Device Under Test

MuPix

α

Provided by DESY

• Beamline T22

• 1 GeV to 6 GeV electrons

• Aconite beam telescope

Alignment 12/

With Misalignment

Track

Hit Sensor

True Position _Residuals

Track Residuals After Alignment

residualX_1 Entries 350029 Mean -0.0001425 RMS 0.00326

-0.020 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 2000

4000 6000 8000 10000

12000 residualX_1

Entries 350029 Mean -0.0001425 RMS 0.00326

Track Residuals X / mm

Rate / a.u.

residualY_1 Entries 350029 Mean 0.0009342 RMS 0.003289

-0.020 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 2000

4000 6000 8000 10000

12000 residualY_1

Entries 350029 Mean 0.0009342 RMS 0.003289

Track Residuals Y / mm

Rate / a.u.

Single Hit Resolution 13/

1.5 1.0 0.5 0.0 0.5 1.0 1.5

Column Residuals

1.5 1.0 0.5 0.0 0.5 1.0 1.5

Row Residuals

Pixel 92 µm

80 µm

0 500

Rate / a.u.

0 200

Rate / a.u.

6 1218 2430 36 4248 54

Rate / a.u.

0° incidence angle 70 V high voltage 823 mV threshold

Global Efficiency / High Voltage 14/

820 830 840 850 860 870 880

Global Threshold / mV

0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00

Efficiency

0° incidence angle E = 5GeV

HV = 50V HV = 70V =

tracks

Global Efficiency / Incidence Angle 15/

820 830 840 850 860 870 880

Global Threshold / mV

0.88 0.90 0.92 0.94 0.96 0.98 1.00

Efficiency

HV = 70V E = 5GeV

0.0° incidence angle 22.5° incidence angle 45.0° incidence angle

Effective thickness∼1/cosα

Pixel Efficiency 16/

0 5 10 15 20 25 30

Column Number

0 5 10 15 20 25 30 35

Row Number

0.980.99 1.00

Efficiency

0.98 1.00

Efficiency

0.10.2 0.30.4 0.50.6 0.70.8 0.91.0

Efficiency

0° incidence angle 70 V high voltage 823 mV threshold

Subpixel Efficiency / 4x4 Submatrix 17/

0 1 2 3

mod(Column Number, 4)

0 1 2 3

mod(Row Number, 4)

0.980.99 1.00

Efficiency

0.98 1.00

Efficiency

0.10.2 0.30.4 0.50.6 0.70.8 0.91.0

Efficiency

0° incidence angle 70 V high voltage 823 mV threshold

Timing 18/

tsdiff

Entries 94666

Mean 2.729

RMS 24.79

/ ndf

c2 1332 / 99

p0 2328 ±36.5 p1 -4.702 ±0.024 p2 1.662 ±0.023 p3 299.9 ±1.8

-40 -20 0 20 40

500 1000 1500 2000 2500

3000 _Entries ^tsdiff ₉₄₆₆₆

Mean 2.729

RMS 24.79

/ ndf

c2 1332 / 99

p0 2328 ±36.5 p1 -4.702 ±0.024 p2 1.662 ±0.023 p3 299.9 ±1.8

Difference Timestamp Hit - Trigger

Timestamp / 10 ns

• External timestamp 100 MHz

• Time resolution 17 ns (Sensor + DAQ)

Summary & Outlook 19/

Mu3e

• Search forµ⁺ → e⁺e⁻e⁺

• Fast and precise electron tracker

• Sensitivity 1 in 10¹⁶ decays MuPix4 Testbeam

• Efficiency>99%

• Position resolution∼pixel size

• Time resolution<17 ns

• HV-MAPS for Mu3e works

Outlook

• MuPix6 prototype

• Scale size

• Full Integration

Summary & Outlook 19/

Mu3e

• Search forµ⁺ → e⁺e⁻e⁺

• Fast and precise electron tracker

• Sensitivity 1 in 10¹⁶ decays MuPix4 Testbeam

• Efficiency>99%

• Position resolution∼pixel size

• Time resolution<17 ns

• HV-MAPS for Mu3e works

Outlook

• MuPix6 prototype

• Scale size

• Full Integration

Thank You

Backup

Mu3e Collaboration A1

• Paul-Scherrer Institute, Switzerland

• ETH Zürich

• University Zürich

• University Geneva

• Heidelberg University

• ZITI Mannheim

HV-MAPS A2

• P-N junction between N-well and substrate

• Reverse bias voltage

• Thin depletion zone beneath N-well

Hitmap a.k.a Hybrid Strixel Sensor A3

0 5 10 15 20 25 30

Column Number

0 5 10 15 20 25 30 35

Row Number

20 40 60 80 100 120 140 160

Hit Count

0° incidence angle 70 V high voltage 838 mV threshold 5 GeV beam energy

Pixel Tuning A4

Before Tuning

0 5 10 15 20 25 30

Column Number 0

5 10 15 20 25 30 35

Row Number

0.98 0.991.00

Efficiency

0.98 1.00 Efficiency ^0.0

0.10.2 0.30.4 0.50.6 0.70.8 0.9 1.0

Efficiency

After Tuning

0 5 10 15 20 25 30

Column Number 0

5 10 15 20 25 30 35

Row Number

0.98 0.991.00

Efficiency

0.98 1.00 Efficiency ^0.0

0.10.2 0.30.4 0.50.6 0.70.8 0.9 1.0

Efficiency

45° incidence angle

Clustering / Charge Sharing A5

Cluster Size

1 2 3 4 5 6 7 8

Cluster Size 10^-5

10^-4 10^-3 10^-2 10^-1 10⁰

Rate / a.u.

= 0.0°

UHV = 70V Uthr = 823mV Ebeam = 5GeV

0° incidence angle 70 V high voltage 823 mV threshold 5 GeV beam energy 1-pixel cluster dominate

2-Pixel Cluster

1.5 1.0 0.5 0.0 0.5 1.0 1.5 Column Residuals 1.5

1.0 0.5 0.0 0.5 1.0 1.5

Row Residuals

Pixel

92 µm

80 µm

pixel0

2 4 6 8 10 12 14 16

Rate / a.u.

1.5 1.0 0.5 0.0 0.5 1.0 1.5 Column Residuals 1.5

1.0 0.5 0.0 0.5 1.0 1.5

Row Residuals

Pixel

92 µm

80 µm

pixel1

2 4 6 8 10 12 14 16

Rate / a.u.

Mu3e Expected Sensitivity over Time A6