The Nikhef organisation
Nikhef is the national institute for subatomic physics in The Netherlands. At Nikhef, approximately 175 physicists and 75 technical staff members work together in an open and international scientific environment. Together, they perform theoretical and experimental research in the fields of particle and astroparticle physics. The Nikhef institute is a collaboration between six major Dutch universities and the Dutch Foundation for Scientific Research (NWO).

Nikhef participates in large research collaborations, including experiments at CERN, the KM3NeT neutrino telescope in the Mediterranean, the VIRGO interferometer in Pisa, the Xenon1T dark matter experiment in Gran Sasso, the Pierre Auger cosmic ray observatory in Argentina and the eEDM research programme in Groningen. Nikhef also hosts a group in theoretical physics, and groups for Physics Data Processing and detector R&D, all with good connections to the experimental programs.

This particular position is located at the University of Twente in Enschede.

The Gravitational Waves group
The gravitational-waves research team at Nikhef counts about 40 researchers distributed equally among staff and junior (postdocs and PhD students) scientists. Its activities include: analysis of data from the Virgo observatory near Pisa; participation in various Virgo upgrade projects;  preparations towards future generation gravitational-waves observatories such as the Einstein Telescope which could be realized underground in the Belgian-Dutch-German border region; and the LISA satellite mission.

The position
Nikhef has a vacancy for a PhD position at the University of Twente as part of a challenging European project that aims to design and realize a third-generation Gravitational Wave (GW) observatory. Due to extreme phenomena in space, such as the merging of two black holes, a gravitational wave spreads over space much like ripples in a pond when a stone is tossed in. These waves travel at the speed of light  and squeeze and stretch anything in their path as they pass by. These waves were predicted more than 100 years ago by Albert Einstein and were first detected only in 2015 using an interferometer-based detector in which the minute change of the distance travelled by a laser beam could be detected. In the European Einstein Telescope (ET) project the challenge is to realize a GW observatory that has an unprecedented resolution. It should be able to detect a relative change in distance of only 1022 m. This is equivalent to measuring 0.015 nm in the distance of Earth to Sun! One of the measures to realize this extreme resolution is to cool the mirrors in the interferometer to an extremely low temperature approaching the absolute zero. This is required to limit the noise caused by thermal activity in the coating of the mirrors. And obviously, this cryogenic cooling has to be free of vibrations. This is where your challenge is.

Your role:
The PhD position is focused on cryogenic coolers for mirrors in the ET observatory. Here, continuous vibration-free cooling is required. The concept is to use sorption-based compressors that have been developed by the University of Twente. These compressors are thermally driven, have no mechanically moving parts and are therefore vibration-free. The Energy, Materials and Systems group (EMS) of the University of Twente has a large experience in this cooler technology based on earlier ESA projects. In this PhD project, carried out at the University of Twente, the sorption-cooler chain has to be designed and experiments will need to be performed for validating modeling and operation.

Requirements:
You have a Master’s degree in Applied Physics, Engineering, Mechanical Engineering or a closely related discipline; Good knowledge/demonstrated awareness of heat and mass transfer and thermodynamics. Experience in the development of and undertaking experiments in low temperature environment is a plus. You possess good knowledge/demonstrated awareness of (numerical) modeling. Excellent analysis skills and an analytical mind-set, as well as excellent communication skills, including written English language proficiency is a must. You have an ability to work independently and as a member of a research team. A collaborative attitude is strongly desired. You are able to review and engage with interdisciplinary studies and are driven by curiosity.
Contact information:
Further information can be obtained from Prof. dr.ir. Marcel ter Brake: h.j.m.terbrake@utwente.nl 

Offer
The candidate will be employed by the NWO-I-foundation and will obtain the status of junior scientist. He/she will receive a 4 year contract. The Working location will be the University of Twente in Enschede. The gross monthly starting salary will be € 2.407,-, increasing to € 3.085,- in the fourth year. The conditions of employment of the NWO-I-foundation are excellent and can be found on www.nwo-i.nl.

Application
Qualified applicants are encouraged to apply by clicking the 'Apply Now' button below. Please be prepared to upload a curriculum vitae, a brief motivation letter and a statement of research interests, as well as to give the email addresses of at least two referees who are willing to send a letter of recommendation on your behalf. Only applications received before the 15th of July 2020 will receive full consideration.