vmm in the magix experiment - cern

Plans and developments for the VMM in MAGIX

Stefano Caiazza

26-Sep-18S. Caiazza - VMM for the MAGIX experiment 2

Status at the Summer collaboration meeting (from M. Lupberger)


Internal Gas Target

•Windowless gas target

• Integrated recoil silicon detectors

•Forward luminosity monitors

Spectrometers

•Twin Arm Dipole Spectrometer

•Zero-degree tagger spectrometer

Focal Plane Detectors

•GEM-based TPC tracker

•Timestamping trigger

A high-precision multi-purpose experimental setup

•Momentum range: ≈ 100 MeV

•Momentum resolution: 𝛿𝑃

𝑃≈ 10−4

•Focal plane length: ≈ 1 m

•Required position resolution: ≈ 100 μm

Momentum measurement

•Sample the particle trajectory in at least two points and perform a linear fit

•E.g. required angular resolution: ≈ 10−3 rad

•Position resolution: ≈ 100 μm

•Minimum plane distance: ≈ 10 cm

Focal plane angle measurement

•Dependent on the specific process under study

•Worst case scenario: elastic scattering in the forward direction

•Spectrometer focusing all particles of the same momentum in a single line on the focal plane

•100 kHz/mm2 at a fixed location.

Expected rates



Extension

plates

TPC

•Open field cage with minimal in-beam material

•Thin field cage in the back to maximize trigger efficiency

•Field plates extensions in the spectrometer vacuum to improve the field quality

•Triple GEM amplification

•No magnetic field

Detector characteristics

•Cartesian pad plane, 20-25 rows of 8x2 mm2 pads

•500-600 pads per row, 12000 channel per detector

Detector readout

•Fast scintillating fibers or crystals behind the TPC

•Option 1: Streaming readout and offline event building/timestamping(10-100 KHz readout rate on about 100 channels)

•Option 2: Triggered readout with or without spectrometer coincidence (<1 KHz coincidences)

Triggering


… x 32 Block 2

Block 3 Block 4

Block 5 Block n

•Sensitive area divided in equal size blocks

•4 rows x 32 pads per block, 32x64 mm2

•Each block connected to a single VMM hybrid directly behind it

•Scalable design that can be extended from the prototype to the final size

Readout plane design

•VMM hardcoded neighborhood algorithm can be used to force the readout of “the next channel” if a channel reads a signal

•In our readout scheme not all neighbor channels are physically next to each other

•Can introduce a reconstruction bias/non uniformity between the channels in the middle of a block and those at the edge

•Needs to be tested (simulation and experiment)

Neighborhood conflicts


• Each hybrid installed behind its block

• Short flexible adapters to connect them to the board

• Mechanical mounting integrated in the board

Perpendicular hybrids

• Cooling bar connecting all hybrids in the same row to an external heat exchanger

• Air or water cooling TBD

Cooling

• Front-end DAQ devices could be placed close to the spectrometers but probably not within 5m (probably need the power boxes)

• Radiation background should be mild and can be coped with minimal shielding (no pions or muons and only a low power beam dump in the hall)

• What is the radiation hardness of SRS?

Hardware positioning

• FECs currently have 1GB connections. This may be a problem, in particular if we go for a streaming readout

• We cannot yet precisely estimate the bandwidth requirements of single FECs (event size and spatial distributions of background tracks unknown)

• We expect high rate but low multiplicity – total event size is small

• Tracks will be concentrated on a small area for most of the time – high occupancy of few hybrids

Bandwidth issues


Work in progress – Very preliminary considerations

• Common project of the RD51currently under development

• We are designing it to be used for large systems like this

• More later

Scalable Readout DAQ

• General experimental framework of the MAGIX experiment

• Direct interface between SR-DAQ and the rest of the simulation, reconstruction and analysis system

MXWare framework

• The accelerator and all the experiments will use an EPICS based slow control system

• We already have an EPICS based slow control for the APV-SRS combination

• We will develop a similar system for the VMM-SRS combo

• Will either be interface with the SR-DAQ or be integral part of it.

EPICS slow control


26-Sep-18S. Caiazza - VMM for the MAGIX experiment

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•10x10 cm2 sensitive surface, 7 cm drift length

•New board in production to test the modular design.

•New VMM connectors on the board

•VMM and APV flex adapter cable under production

•Test-beam planned 8-11 November 2018 at MAMI in Mainz

Small prototype

•Build a simple benchmark prototype to be easily used at test-beams and in the laboratory

•Test the quality of the readout board and validate the usage of the VMM for a TPC

Small prototype goals

•30x30 cm2 sensitive area, 15 cm drift length with thin field cage and extension module

•Test a 2 FEC system (16 hybrids) to evaluate the scalability, and the synchronization

•First results need to be available by June 2019

1 year plan


•Validation and technology choices should be done in summer 2019

•If the choice is approved by the collaboration and by the funding agencies the purchase of a large electronics system can proceed

Timescale

•2 x 12000 channels

•2 x 96 hybrids – 12 FEC and 12 Dcard per detector

•200 hybrid + spares (at least 5 wafers)

•SRU, power boxes and all the additional support electronics

TPC electronics

•Silicon recoil detectors and scintillator

•I would love to be able to read them all with the SRS. How difficult would that be?

Other electronics


Assuming the VMM-SRS system is validated and accepted by the collaboration

• Dedicated test-beam line for detector development on the MAMI-B accelerator

• 195-855 MeV electron pencil beam with several nA current

MAMI detector test beam

• Dedicated test-beam slot scheduled for MAGIX detector test

• Test the small TPC prototype we are building

• First evaluation of the VMM electronics.

• First beam test of the new SR-DAQ(?)

• Michael Lupberger will be joining us to help us operate the VMM

8-11 November 2018

• Test the VMM in the lab with the TPC and the standard strip-based CERN detector

• Basic characterization of the TPC at the test beam using both VMM and APV

• High rate test of the VMM detector in beam with TPC and strip detector

• Take the same data sets with APV and VMM for comparison

Current plans


26-Sep-18S. Caiazza - VMM for the MAGIX experiment

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vmm in the magix experiment - cern

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