Detector systems / CERN

Making 164 detector channels act like one instrument.

MilliQan searches for particles carrying a tiny fraction of the electron's charge. I engineered and installed the acquisition path that turned photomultiplier signals into detector data.

Hardware integrationCAEN V1743 waveform digitizers during functional testing

Scale164 detector channels

FirmwareVerilog trigger logic

SoftwareC++ and Python

EnvironmentInstalled at CERN

My responsibility

The interfaces that make detector data trustworthy.

I worked across digitizer integration, FPGA trigger logic, control software, hardware test routines, assembly, and installation. The engineering problem was to make a multi-board system behave as one observable and testable instrument.

That required moving comfortably between the waveform on the oscilloscope, the digital trigger path, the C++ control layer, and the Python tools used to exercise hardware. A failure at any one interface could appear somewhere else, so the system had to be checked from the physical signal outward.

System architecture

Two paths, one event.

The data path captured detector waveforms. The trigger path decided when those waveforms became an event worth recording. Control and test software made both paths configurable and inspectable.

Data path

DetectorPMT signals

DigitizationCAEN V1743 array

OutputWaveform data

Trigger path

InputsTrigger groups

DecisionFPGA trigger firmware

ReturnAcquisition trigger

System control and verificationC++ control software · Python hardware tests

Oscilloscope showing a digital test signal and the measured electronics response — Test 01 / Signal responseFollowing the commanded signal into the measured electronics response.

Stack of CAEN high-voltage distribution boards prepared for detector assembly — Test 02 / Detector electronicsCAEN high-voltage distribution hardware prepared for integration.

Joe Crowley wearing underground safety equipment while installing MilliQan hardware at CERN — Field 01 / CERNOn site for detector assembly and installation in 2022.

Testing and commissioning

Make every interface visible.

Configure

Establish reliable communication with the digitizers and control their operating state from software.

Stimulate

Exercise the electronics with known inputs and inspect the resulting waveform and trigger behavior.

Integrate

Bring the boards, firmware, and control software together as a coordinated acquisition system.

Install

Assemble and commission the detector electronics at CERN for the Run 3 system.

Result

The system left the bench and went underground.

The acquisition system was installed at CERN for the Run 3 detector. The collaboration later reported the bar detector operational and collecting LHC collision data.

My responsibility was the DAQ, trigger firmware, hardware tests, assembly, and installation described here. Detector-wide operation belongs to the MilliQan collaboration.

Project sources

The collaboration record.

These external sources establish the detector design, public DAQ architecture, and later project status. This case study identifies my individual contribution.

Run 3 detector designPhysical Review D, 2021 Public DAQ architectureDark Interactions workshop, 2022 Detector statusICHEP, 2024

The larger engineering story

Hardware, firmware, software, and evidence belong together.

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