The MuPix Telescope

Timedifference between track and hit [32 ns]

−10 −5 0 5 10

Entries [1/run]

102

103

104

Threshold [V]

0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025

Efficiency

0.93 0.94 0.95 0.96 0.97 0.98 0.99 1

Rotation 0° 15° 30° 45°

)/2 (ns) -t2 (t1

-4 -3 -2 -1 0 1 2 3 4

Events/200ps

0 2000 4000 6000 8000 10000 12000

The MuPix Telescope

Integrating a novel HV-MAPS chip into a tracking detector system

Lennart Huth ¹ on behalf of the Mu3e Collaboration

1) Physikalisches Institut, Heidelberg University, huth@physi.uni-heidelberg.de

Detector Concept

Pixel Detector

Timing Detector

Target Beam

Summary & Outlook

MuPix Telescope Testbeam Results

Motivation μ ⁺ →e ⁺ e ^- e ⁺ Background

New physics is predicted to be observable in lepton flavour violation and many theories predict measurable violations also in charged currents. The decay of a muon into three electrons is currently excluded to a branching ratio (BR) of 10-12 by SINDRUM¹. Any observation would be a clear sign for new physics. New detector technologies allow for a more precise measurement. Mu3e is going to search for this decay with a target sensitivity of 1 in 1016 decays.

A continous high rate beam at PSI will provide up to 108 muons/s (109 muons/s on future beamline), which will be stopped on target. The decay particles are tracked in a constant magnetic field using four thin pixel layers and additional timing detectors.

The pixel tracker will be constructed out of a novel high voltage monolithic active pixel sensor (HV-MAPS) technology.

For testbeam characterization and intergration studies, a particle tracking telescope was developed.

¹ [SINDRUM Collaboration] "Search for the decay muto3e" Nucl. Phys., B299 1,1988

Signal Topology

• Common vertex

• Coincident in time

• Σ p = 0

• E < 53 MeV

• E^tot = m^μ

Internal Conversion μ⁺→e⁺e^-e⁺ν_eν^μ

• E^tot ≠ m^μ

⇒ Suppressed by good momentum resolution

Accidental Background

• No common vertex

• Incoincident in time

⇒ good time and vertex resolution

• HV-MAPS technology

• 270 Mio pixel

• Fully integrated readout on-chip

• 80 x 80 μm² pixel, 4 cm² chip

• 50 μm thin

• < 20 ns time resolution

• Kapton^TM support frame

• 1 ‰ radiation length per layer

Thin Fibres

• 250 μm per layer

• 3 layers

• 500 ps

Thick Tiles

• 1 cm² per tile

• 100 ps

• Electrons stopped

• 75-85 μm Mylar

• Large surface

⇒ vertex separation

• Stopping power: 95 %

Magnet

• 1 T

• 1m diameter

• 3m long

σ = 500 ps

Run number

320 340 360 380 400 420

Residuals x mean [um]

−15

−10 5

− 0 5 10

Residuals in x for plane 0 Residuals in x for plane 1 Residuals in x for plane 2 Residuals in x for plane 3

Run number

320 340 360 380 400 420

RMS of residuals x mean [um]

15 20 25 30 35 40 45 50

RMS of residuals in x for plane 0 RMS of residuals in x for plane 1 RMS of residuals in x for plane 2 RMS of residuals in x for plane 3

Software Alignment

Mean Sensor Efficiency Performance Setup

0 1 = DUT 2 3

Beam

6cm 2cm 6cm

α

@DESY (Hamburg)

Threshold [V]

0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02

Efficiency

0.75 0.8 0.85 0.9 0.95 1

1 W/cm² 400 mW/cm² 300 mW/cm² 225 mW/cm²

@PSI (Villigen)

Mu3e

• Large scale pixel sensor prototype 2nd quarter 2016

• Detector module by the end of 2016

MuPix Telescope

• Useful tool for integration test and testbeams

• High system efficiency (≈ 99%)

• Evaluate next sensor prototypes

Details

Mechanics DAQ System

200-260mm

max. 600 mm min

25 mm

breadboard

rail MuPix Beam

1

Sorter

Time Frames

on FPG A

HDD

GUI

2 3 4

Sensor Control

Monitoring

• Based on Thorlabs

^TM

components

• PCB holder custom design

• 10 μm precision in x/y

• Stable and compact

Acknowledgments

I acknowledge support by the IMPRS for Precision Tests of Fundamental Symmetries.

The Mu3e team wants to thank the Helmholtz alliance for providing beam time.

We also like to thank PSI for providing beam time.

Time Resolution

• Max track rate: 2 MHz

• Mechanical precision: 100 μm

• Automized measurement procedures

• Direct memory access and

GPU tracking successfully tested

e

⁺

e

⁺

e

^-

e

⁺

e

⁺

e

^-

DMA Design Goals

• Track rate capability: 20 MHz

• Time resolution: 10 ns

• Position resolution: 150 μm

• Online tracking

• Tracking efficiency: 90%

σ=14.3 ns

Sensors

R. M. Djilkibaev, R. V. Konoplich, Phys.Rev. D79 (2009) 073004)

@DESY (Hamburg)

@DESY (Hamburg)

tree level cLFV

loop cLFV

• Accelerator:

HIPA at PSI

• Up to 10⁸ μ/s

• p= 28 Mev/c²

• Future beamline: 10⁹ μ/s

Residuals < 4μm