ATHENA - Module Construction P. Riedler, J. Rochet

1. ATHENA ATHENA is an experiment at the CERN antiproton decelerator (AD). The first run took place in August Goals: Antihydrogen production Longterm goal (2-3 years): CPT-test with a precision of (spectroscopy of 1S-2S) Unambiguous detection Study of recombination

A detector system surrounds the recombination zone to detect H via its annihilation signals: Charged pions 2 x 511 keV  “back-to-back” Silicon strip detectorsCsI crystals + photodiodes Determine the charged vertex and check the collinearity of the 2  within a time-window (~1µs). 2. ATHENA Vertex Detector

Petra’s activities (Nov March 2001) in ATHENA: Silicon Vertex Detector: Strip detector design and design checks for 77K Tendering and industry contact for production of silicon detectors Testing and QA Development of module design for 77K environment Construction of all ATHENA silicon strip modules Beamcounter: Development of ultra-thin silicon beamcounter (6-67µm) for 5.3MeV antiprotons at 10K (5x10 7 mips per µm)

Cylindrical symmetry Outer diameter: mm Inner diameter: 75 mm Length: mm Temperature: 77K Vacuum: mbar 16-fold symmetry 2 layers Si strip-detectors 192 CsI crystals with Si photodiodes 8960 read-out channels Schematic cross-section of the ATHENA vertex Detector

Outer layer

Inner layer

3. Modules

4. Constraints Double sided strip detectors o handling o connections on both sides required Temperature range: 77 K-300 K o mechanical stability (different TEC) - BUS! o glue Two layers of double sided detectors within 37.5mm radius o bonds o mounting

5. Gluing and matching of the module components Glue: araldite W106 low temperature mixture (50:50) (Advice from the group of M. Hominal at CERN) Temperature cycling (300K-77K-300K)

Reliable Regular Repeatable Commercial glue dispenser + Alignment setup with microscope 5.1 Glue Deposit:

Final setting glue drop for 18s every 10.6mm, 3bar N 2 Alignment hole on the jig for needle

Tests to define: Duration Needle diameter Pressure Step width Weight Silicon Glas Always weigh the two components of the glue!

Production of prototypes: Prototype 0: 160 mm Si + PCB hybrid + capton (V0) Prototype 1: 162 mm Si + alumine hybrid + alumine bus (V1) Prototype 2: 162 mm Si + alumine hybrid + glass (D263) bus (V1) Prototype 3: 162 mm Si + alumine hybrid + alumine bus (V1) Prototype 4: 162 mm Si + alumine hybrid + glass (AF45) bus (V1) Prototype 5: 162 mm Si + alumine hybrid + carbon bus (V1) Prototype 6: 162 mm Si + alumine hybrid + silicon bus (V1) 5.2 Material matching

Tests with lN 2 Alumine bus - prototype module seen from the side at lN 2 temperature Glass bus - prototype module seen from the side at lN 2 temperature The silicon detectors did not break!!!

Thermal expansion coefficients: Capton~30 ppm/K Alumine ppm/K Glass D ppm/K Glass AF ppm/K Carbon2.1 ppm/K Silicon ppm/K (~40µ deviation) Bus: Produced on 200mm Si wafer (400µ) Chr-Al-Ti-Ni-Au on 10µ polyimide (bonding tests!) Laser-cutting NEW!

Precision: <100µm over the full detector length required (164 mm) Align the detectors to one reference line on one jig no alignment in z required! Microscope reference: n+ implantation edge 6. Module Construction

1. Align first detector to setup

2. Align second detector to referene line measure deviation over full length Distance piece for bus Reference line

3. Apply glue Weigh the two components (Mettler-Toledo)

4. Bus mounted control if pads on detector and bus are well alined mount fixation (recheck alignment) Remove chuck from alignment station (store 24 hours)

Cals put onto lense-paper on top of the bus (1.125 kg)

5. Gluing jig for hybrids

5. Bonding

Built 37 modules in 24 days hours work on the alignment setup per module Parallel work on the hybrid mounting (0/0) n+ implant edge