Technology at Nikhef

Electronics Technology

Research into new phenomena and as-yet-unknown subatomic particles requires specialized measuring instruments and custom electronics. These are often not commercially available and require close coordination with the researchers at the experiments. They are developed by the Electronics Technology (ET) department for experimental setups such as those at the LHC accelerator at CERN, the Virgo laser interferometer, and the KM3NeT neutrino detector.

How does ET operate?

The department designs, manufactures (or has manufactured), and maintains the specific electronics—both small and large—and delivers them with the appropriate reliability and quality.

Electronics are developed in various fields for multiple projects, with close coordination between designers and scientists.
The department has an extensive range of instruments and specialized facilities.
The diverse expertise of the ~25 ET staff members (engineers and technicians) makes the department strong and flexible.

The department operates on a project-based approach and frequently collaborates with other institutes (often European, but also worldwide) as well as working multidisciplinary with Nikhef’s Computer Technology (CT) and Mechanical Technology (MT) colleagues.

Attention is given to training in and the use of new techniques, aligned with the state of the technical expertise and in collaboration with industry and in the outsourcing of production work.

What are ET’s areas of expertise?

Analogue electronics

The foundation of electronics lies in the use of semiconductors in electrical circuits. The origin of an electrical signal can always be described as an analogue signal; involving current (charge) and/or voltage, and often with an alternating frequency. The first circuits are then amplifiers and filters, followed by analogue-to-digital converters. Because Nikhef is a research laboratory, specific electronics are often required for measurements using sometimes specialized sensors and detectors. Or for environments involving radiation, in a vacuum, or at low temperatures.

Electromagnetic fields arise around electronics, and these can also be measured. This is important for the optimal functioning of the circuits and in relation to European directives laid down in Electromagnetic Compatibility (EMC) CE standards to prevent interference.

To measure our own electronics, testing can be performed in a special Faraday cage, a fully metal EMC chamber equipped with associated instruments and antennas.

Digital electronics, FPGA design

FPGAs are used for processing digital signals, such as digitized data from detectors. These are programmable and configurable chips with logic capable of performing various complex functions, which are configured by the firmware. Often, an FPGA also incorporates a CPU for communication and other functions. This requires specialized design software to describe the functions, simulate them, and ultimately program them into the FPGA. It also facilitates collaboration with software developers and enables joint work on a single project. Work on configuring an FPGA is carried out both individually and as part of a team.

PCB Design

All electronics are ultimately manufactured on a “Printed Circuit Board” (PCB). Electronic components are soldered onto this board using Surface Mount Technology, and electrical connections are made between them. Large FPGAs (more than 1,500 pins), high-speed data signals (10 Gb/s or more), and sensitive analogue signals from a detector—all of this is integrated onto a single PCB, which is sometimes constructed from more than 20 layers of copper. To design this, ET has specialized knowledge and design software, as well as simulation tools to verify the desired properties of the PCB prior to production.

The production of the PCB and its assembly with components is fully outsourced based on the data files generated by ET.

Full-custom IC design

When desired electronic components are not commercially available, we can also design them ourselves. For use in radiation environments, or for very specific functions such as in sensors and detectors, or for small-volume production, it is sometimes necessary to design integrated circuits (ICs) in-house. For this purpose, the group employs specially trained engineers who can realize these designs using IC design software. CMOS technology is primarily used. Both specific analogue circuits and many digital functions can be integrated into ICs; this is often done in design teams composed of designers from various universities and institutes (CERN, Bonn, Marseille, BNL/USA, etc.). We use 180nm, 65nm, and 28nm CMOS technologies.

IC design at Nikhef is made possible by software tools provided through the European organization “Euro-Practice” for universities and research laboratories.

Optical techniques

In large-scale experiments, such as those at CERN and KM3NeT, vast amounts of data are generated. This data must be transmitted and processed at high speed. For longer distances (10m and up), it is often more advantageous to use fibre-optic cables. This requires specific materials, expertise, and test equipment. It is possible to transmit multiple (>100) colours of light, each carrying its own information, through a single fibre, thereby achieving very high data density. An optical laboratory has been set up at ET to support these developments.
What facilities does ET have at its disposal?
ET Test and Measurement Equipment
- Various oscilloscopes, ranging from 300 MHz to 26 GHz (sampling) and a 33 GHz (real-time) model, as well as logic analysers from Agilent, LeCroy, and Tektronix.
- Various (active) oscilloscope probes, including differential, optical inputs, and high-voltage probes.
- Vector network analyser up to 20 GHz from Keysight and a phase noise analyser (26 GHz) from Rohde & Schwarz.
- Pulse and signal generators, 10 MHz – 12.5 GHz + bit error rate tester.
- A range of programmable power supplies, 0–5V, 0–300V, 0–5kV, 0–20A, plus Source Measurement Units (SMUs) from Keithley.
Specialized lab spaces
- An EMC chamber for sensitive measurements and CE pre-compliance; attenuation 100dB, 0–18GHz.
- An Optical Lab for working with fibre optic cables and optical components, fibre splicing, optical workbench, OTDR, optical spectrum analyser. Primarily for optical data communication.
- Small mechanical workshop, including: PCB milling machine for prototype PCBs & small workpieces in fiberglass material (FR4). And a coil winding machine.
- PCB rework: SMD BGA rework station (Pace) + associated tools and high-quality soldering and desoldering workbenches for working with SMD components.
- 2 climate-controlled cabinets for conducting stress tests on various components and modules.
WWhy does Nikhef have its own Electronics Technology department?

Many of the components used in the international (astro)particle physics research facilities to which Nikhef contributes are entirely unique, meaning they simply cannot be purchased off the shelf. Instead, they must be designed and manufactured in-house at Nikhef to meet the exceptionally strict standards set by the (astro)particle physics community.
What projects is ET working on?

KM3NeT

Nikhef is actively involved in the production and development of a large neutrino telescope at the bottom of the Mediterranean Sea, called KM3NeT. The experiment will be equipped with ~400,000 Photon Multiplier Tubes (PMTs) as detector elements, and the data will be transmitted via optical connections to shore in Italy and France.

Nikhef’s contributions in the field of electronics are: The readout of the PMTs using a specific PMT base: low power, low cost with 2 ASICs (Application-Specific Integrated Circuits). One ASIC to amplify and digitize the signals, and the other to generate and regulate the high voltage for the PMT (1500V). In addition, a DC/DC converter has been developed for the power supply of the optical modules, which is resistant to 400 bar water pressure, and the underwater optical network up to shore for data communication. Timing distribution using White Rabbit technology has also been implemented, enabling every sensor in KM3NeT to measure the detection of a photon with an accuracy of a few nanoseconds.

LHCb

ET is working on new readout electronics for the upgrade of the LHCb muon detectors with Scintillating fibers (SciFi). Front-end boxes have been developed, featuring ~600 FPGA boards for reading out all data and configuring the front-end ICs. For the detector frames (6 m high), the cable routing has been designed within the very limited space between and around the sensors.

Starting in 2026, ET will begin work on a new vertex detector, featuring new electronics and integrated cooling structures, in collaboration with colleagues from the Mechanical Technology department.

ATLAS

For an ATLAS upgrade, the team is working on a new readout system (Data Acquisition: DAQ); FELIX. This system, consisting of a plug-in card for a powerful computer server, can receive and forward large amounts of data, thereby routing detector data to the appropriate computers for data analysis and storage. The data is organized and time-stamped. It consists of hardware—the plug-in card with a large FPGA—and extensive software.

This is being developed through an international collaboration, and Nikhef plays a leading role in this effort. Meanwhile, several other detector groups within ATLAS, as well as ALICE and LHCb, have expressed interest in this system. Due to its reconfigurable hardware, it can be adapted for use in those experiments as well.

ALICE

The ALICE experiment aims to upgrade its Inner Tracker for the next upgrade of the LHC accelerator. This will enable larger numbers of events to be measured with greater precision. This ITS3 will consist primarily of Monolithic Active Pixel Sensors (MAPS), which are large integrated circuits in which both the sensor and the readout electronics are integrated. Nikhef’s ET department is collaborating on this IC development with CERN and others, by specifying, designing, and testing various circuits and functions within the IC.

Virgo: Clock Signal Distribution

For the Virgo upgrade, a clock distribution system based on White-Rabbit technology has been developed. This ensures that the clock signals required by the control circuits and measurement systems in Virgo all operate simultaneously at a fixed frequency, with high precision and stability. What makes the White-Rabbit system special is that it achieves this with very high accuracy and stability, representing an improvement over the current method. This will also be applied to ETpathfinder in the future.

ETpathfinder: photodiode readout

Monitoring and control of the optical system are required at various locations around the laser interferometer. This is done using 4-quadrant photodiodes (QPDs). Work is underway on the specifications for the custom-made QPDs, and readout electronics will be developed.

Detector R&D

For future upgrades to the Tracker detectors in the HL-LHC, at LHCb, and ALICE, work is underway on new ASICs and pixel chips capable of measuring the arrival time of detected particles with an accuracy of 30–50 ps.

ET is working on circuits for these ASICs, using 65nm and 28nm IC technologies, which must be radiation-hardened. This includes data transmission (serializers), output drivers, digital-to-analogue converters, power regulators, phase-locked loops, and voltage reference circuits.

Because clock and timing distribution are critical for various experiments, further development is underway on White Rabbit. This involves calibration methods, standardization agreements (e.g., IEEE), generic hardware (the baby white-rabbit card), and improvements in stability and accuracy.

R&D Einstein Telescope

For measurements of seismic background noise for the future Einstein Telescope, a MEMS-ASIC system is being developed in collaboration with Innoseis that can measure the smallest seismic vibrations with high precision. Nikhef developed an ASIC, and Innoseis developed the MEMS sensor, and together they are working on the system.
How is the collaboration with the Nikhef research and technical groups?

The ET department works closely with the LHC research groups to develop new electronics for the experiments there. In addition, ET collaborates with the Detector R&D department on ASICs for new sensors and sensor testing, as well as readout systems for lab test setups, such as SPIDR. SPIDR is a readout system for pixel ASICs. This is done in collaboration with Nikhef’s mechanical engineers (MT) and software engineers (CT).
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