stephan haensel

Stephan Haensel - 6th SiLC Meeting - Torino

Silicon Envelope for the Large Prototype TPC @ DESY

Stephan Hänsel

Institute of High Energy Physics, Vienna

6th SiLC Meeting - Torino


Contents

• Introduction• Overview of the Experiment• Silicon Envelope• Cosmic Setup• Outlook• First Prototype


Introduction

• The SiLC collaboration will participate at the Large Prototype TPC (LPTPC) at the EUDET facility at DESY II.

• SiLC will design, build and install position sensitive detector modules around the LPTPC made of silicon microstrip sensors that can be used as telescope.

• The design will allow an easily exchange of the modules to enable tests of different sensor- and chip- designs.

• This setup will also help to verify if a silicon envelope for a future linear collider TPC is reasonable.


EUDET facility at DESY II• a bremsstrahlung beam is generated by a carbon fibre

inside the e+/e- synchrotron DORIS II• the photons get converted to e+/e- -pairs with a metal plate• the beam is selected in sign and spread out into an

horizontal fan with a dipole magnet• the final beam gets cut out of this fan with a collimator• typical momentum of electrons reaching beam line T24: 1 to

6 GeV/c, spread ~ 5%, divergence ~ 2mrad


Top view of the Setup

(Drawing from: http://www-flc.desy.de/tpc/)

ID of magnet inner bore 850 mm measured minimum 846 mmSiLC detectors 2 x 35 mmclearance inside of SiLC 780 mm extra clearance 2 x 5 mmOD of field cage 770 mm field cage wall 2 x 25 mm ID of field cage 720 mm

radial dimensions:


• A PCMAG coil built by KEK was already installed in the DESY test beam are T24 in December 2006 and in July its field was measured.

Magnet and TPC

• the TPC field cage design was made on the basis of smaller prototypes

• the end-plate will contain a number of ’windows’ into which pad panels will fit

different readout systems (GEMs, Micromegas, …) will be tested

two thin layers of glass-fibre reinforced plastic, honeycomb Nomex as spacer

(Pics from K.Dehmelt)

Bmax ~ 1,25 T


Silicon Envelope• four silicon modules will be installed:

- two in front and two behind the TPC, with respect to the e--beam two independent support structures are needed

- on each side: one horizontal module consisting of two daisy-chained sensors and one vertical module consisting of one sensor

• movable support system is needed because it must be possible to scan the TPC- the TPC and the magnet will move relative to the beam

TPC Magnet

Beam

Rails Module

- the sensors have to stay inside the beam line

sensors must be movable orthogonal to the beam and along a curved rail this movement must be coupled with the movement of the TPC and the magnet in addition the two sides have to move independently from each other


2D LayoutMagnet

Beam

1 Sensor Module

2 Sensor Module

radial dimensions: magnet inner bore 425 mm measured minimum 423 mmSiLC detectors 35 mm on

radiusclearance inside SiLC 390 mm

it is possible to build an envelope which only needs 25 mm on radius

would give an essential 5 mm clearance to surroundings

sliding carriage

TPC

Sensor Readout• based on APV25 (CMS-hybrids)• IEKP Karlsruhe will provide the readout

system • it is foreseen to replace parts of the CMS

readout system with newly developed electronics containing the SiLC readout chip in the future


Modules

Sensors • single sided AC coupled sensors from Hamamatsu Japan

size: 91.5 x 91.5 mm, thickness: 320 μm1792 readout strips with a strip pitch of 50 μm

• first setup: only 768 channels can be read out the readout sensitive area is reduced to 38,4 x 38,4 mm²

(only the intersecting readout area of the two modules on top of each other is interesting)

sensor details -> Talk of T. Bergauer: “Silicon Strip Sensor R&D and results from HPK sensor measurements”


Modules

Front-End Hybrids including Pitch Adapter• Start up:

hybrids leftover from the CMS Tracker End Cap module production will be usedalready assembled

and bonded• Later on:

replacement with newly developed FE chips


Modules

Intermediate Pitch Adapter• to connect a pitch of 143 m (CMS-R2) with a pitch of 50 m (new HPK)• 2 different PA ordered: ILFA GmbH

4-layer printed circuit board (PCB) two layers of Cu-lines with 100 μm

pitch glued staggered and shifted on top of each other

Helsinki Institute of Physics (HIP),Academy of Finland Aluminium on quartz


Modules

Isoval®11 FrameIsoval®11 is a composite of resin epoxy reinforced with a woven fibreglass mat• high rigidity• low mass • insulator• easy to mechanically processmodules are not glued but get clipped to the frame with 3 mm thick Isoval®11

pads which get screwed to the frame-> easy exchange of modules to enable tests of different sensors and FE chips


Modules

HV Kapton Foil• deliver the HV bias voltage to the sensor backplane• isolate the sensor backplane from the carbon fibre profiles• modified leftovers of the CMS sensor recuperation campaign are used

they contain already RC circuits to stabilize the HV line

Wire Bonds• standardised ultrasonic wire bonding with a Delvotec 6400 automatic bonding machine• aluminium wires: 25 μm diameter including 1% silicon


Modules

Carbon Fibre Beams• backbone of each module consists of two carbon fibre T-beams• for such a low quantity it’s not affordable to order perfect profiles from a company

SECAR Technologie GmbH provided rectangular beams not maximised in terms of radiation length and rigidity two such beams get glued together with a thin film of

araldite glue to form a T-beam which is rigid enough to support the sensors, pitch adapter and the front-end hybrid


Moveable Support System• two aluminium sliding carriage for the silicon modules get build by IEKP

Karlsruhe– movement of the two diagonally arranged frames, containing the

silicon modules, independently in both, phi and in z direction• phi-direction: curved rails mounted at the outside of the magnet

and at the beginning of the magnets bottleneck• z-direction: the sledges move along two round rods via a

threaded rod

Rails


Cosmic Run I

• beam shutdown at DESY in the first half of 2008

the test beam will not be available before August 2008

• in the meantime: perform first tests with cosmics

• TPC cosmic setup is expected to be finished in Feb. 08

• we will participate at the Cosmic Run

gain experience in operating the readout systems of the silicon modules and the TPC together

join the experiment right from the beginning

(Drawing from K.Dehmelt)


Cosmic Run II• design of the silicon envelope has to be changed:

modules will be installed at the top and bottom of the TPC which interferes with the support plates of the TPC

sliding carriage for the cosmic run silicon envelope only needs to be moveable in z-direction

no changes are needed on module level• very rough estimation expects only about 20 Muon coincidences per day in

the intersecting readout

areas of all four silicon

sensors

readout of 768 sensor strips lead to a small sensitive area of only 38,4 mm width per module


Outlook• first prototype (broken CMS-R2 hybrids, dummy sensors and dummy

intermediate pitch adapter – next slide) was already shipped to IEKP Karlsruhe -> they will soon build the sliding carriage

• the needed space for the envelope has to be fixed in agreement with the TPC support structures

quite narrow in cosmic setup no interference in final setup

• it has to be defined were the envelope support can be fixed most probable at the outside of the magnet and the beginning of

the magnets bottleneck via curved rails

• the intermediate PA are ordered but not delivered and tested

• HPK sensors already passed QA tests

• APV readout system details will be determined in Jan. 2008

Everything looks promising towards a start of the cosmic run in the first quarter of 2008!

The cosmic run is a great possibility to make first experiences with the modules, the readout system and a simplified module support system.


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BACKUP Slides


3D Layout

TPC

Magnet

Beam

Rails

1 Sensor Module

3D Layout

2 Sensor Module



HPK Sensors (6 needed for this setup)

Will be delivered in the end of September.

- single-sided AC coupled SSD

- Sensor size: 91,5 x 91,5 mm² (± 0,04 mm)

- Wafer thickness: approx. 320 μm

- Resistivity: such that depletion voltage: 50 V < Vdepl < 100 Volt- Leakage current: < 10 μA per sensor

- Biasing scheme: poly-Silicon Resistor with 20 MW (± 5 MW)

- Number of strips: 1792 (= 14 x 128)

- Strip pitch: 50 μm pitch, no intermediate strips

- Strip width: 12.5 μm

- Dielectric Structure: Oxide (SiO2) + Nitride (Si3N4) between p+ and aluminium strips. (Thicknesses like for CMS)

- 2 bond pads on each side of the strip (CMS size)

- 1 probe pad on each side of the strip (contact to p+)

Wafer Layout

91,5 x 91,5 mm

stephan haensel - 6th silc meeting - torino silicon envelope for the large prototype tpc @ desy...

Documents

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silc collaboration

silc detectors2 x

bremsstrahlung beam

final beam

desy test beam

beam line sensors