Project acronym: ULTI
Project full title: Ultra Low Temperature Installation
Contract no.: RITA-CT-2003-505313
Transnational Access
1.
Project objectives and summary
The Low Temperature Laboratory (LTL) of Helsinki University of Technology (HUT) offers expertise, facilities
and equipment for outside users to undertake measurements at temperatures from 4 K down to the lowest
attainable to date. ULTI is expected to contribute to scientific progress and technical development in ultra low
temperature physics, to serve as a first-rate educational centre for young physicists and, because of its longstanding connections with the low temperature research in Russia, to act as a node for scientific collaboration
between Russia and EU-countries.
The in-house research includes experimental programs on refrigeration, cryogenics and nanofabricated
cryosensors, experimental and theoretical studies of quantum fluids and solids, nuclear magnetism, and electrical
transport in nanostructures. The local low temperature research staff consists of 35 persons of whom 6 are
professors, 4 senior scientists, 4 senior scientists, 5 post-doctorals, 5 technicians and 2 secretarial employees; the
rest are graduate and undergraduate students. The refrigeration equipment includes three nuclear cooling
cryostats capable of reaching sub-mK temperatures and five 20-mK cryostats. As a new addition to our facility,
we offer the users full access to our 55 m2 semi clean room with electron beam lithography line as well as
limited access to a 2600 m2 clean room, jointly operated by HUT and VTT, the neighbouring State Research
Centre. The personnel of the HUT/VTT clean room have expertise on design and manufacturing of
nanofabricated cryosensors, both electrical and micromechanical.
Of the total research activity at the ULTI installation, at most 18% will be allocated to the ULTI visitors. On
average at any given time 1,5 EU-sponsored Users would work in the LTL, and about 40 persons participating in
35 different projects could benefit from the ULTI in four years.
2.
Project website: http://www.ltl.tkk.fi/eu.html
3.
Start date: 1 April 2004
Duration: 48 months
4.
List of participants
The following legal entities are participants to the contract:
Partic.
Role*
Partic.
no.
Participant name
Participant
short name
Country
Date enter
project
Date exit
project
CO
01
Helsinki University of
Technology/Low
Temperature Laboratory
LTL
Finland
1.4. 2004
31.3. 2008
02
03
*CO = Coordinator CR = Contractor
5.
Access modalities
Contact info at http://boojum.hut.fi. Researcher and students interested in experiments at ultra low temperatures,
please contact:
Prof. Mikko Paalanen
Low Temperature Laboratory
Helsinki University of Technology
P.O. Box 2200
FIN-02015 HUT
Phone: +358-9-451 2957
Fax: +358-9-451 2969
E-mail: paalanen@neuro.hut.fi
6.
Achievements
During the first year the supported projects have covered a variety of topics from vortex physics and turbulence
in superfluids, to cosmology in condensed matter physics, and to quantum electronics in mesoscopic normal
metal and superconducting structures. Two of the projects have been already completed. The research activities
funded by ULTI produced 2 publications. At the same time 13 publications, which were based on the work done
during the ULTI III program, were written and published during this reporting period.
One of the remaining problems in classical physics is turbulence. Turbulence occurs in normal as well as in
superfluids, and its closer investigation in superfluids may shed light onto the classical problem. The majority of
the ULTI projects (# 1, 3, 6, 10, 11, 13, and 16) were dealing with the investigation of turbulence in superfluid
3He. In superfluid 3He, the viscosity is a strong function of temperature and for the first time the effects of
viscosity can be studied in detail. The onset of the turbulence is found to be covered by two Reynold’s numbers,
one related to the vorticity and the other one to the mutual friction between the vortices and the quasiparticles.
The Kolmogorov cascade, describing the energy flow from long to short length scales, is also found to be altered
by the mutual friction.