1. Description of the infrastructure, Relevance and S&T Excellence
(in charge: S. Broendsted Nielsen )
1.1 The storage ring ELISA and the low-energy accelerator SEPI with associated equipment is situated at the University of Aarhus in an underground area in direct connection to the building complex of the Department of Physics and Astronomy (building 526). The physical location is on the university Campus in the centre of Aarhus at Langelandsgade and Ny Munkegade, see www.au.dk/en/map, with access through the reception of the Department of Physics and Astronomy.
The infrastructures ELISA and SEPI are operated by the Department of Physics and Astronomy. The facilities are owned by the University of Aarhus, Nordre Ringgade 1, DK-8000 Aarhus C, Denmark.
The electrostatic storage ring ELISA was commissioned in 1999. It was the first of its kind in the world. It presently remains unique although another is operating in Japan. Being entirely electrostatic, the ring can store ions of fixed charge and energy with arbitrary mass. It is therefore particularly useful for the study of heavy ions, clusters (including fullerenes) and biomolecules (nucleotides, peptides and proteins). A new research direction, which includes biomolecules, was initiated with the construction of an electrospray ion source for transfer of biomolecular ions from solution into the gas phase. The electrospray source has been extended with a multipole ion trap to bunch the ions for injection into ELISA. The pulsed beam from the multipole trap enters ELISA (shown schematically in Fig. 1) through a differentially pumped beam line. The circumference of ELISA is 8.3 m and, as can be seen on Fig. 1, the ring consists of two 160° cylindrical deflections with a 10° parallel-plate deflection and an electrostatic quadrupole doublet on each side of the deflectors. Once injected, the ions circulate in the ring until they change their value of energy/charge. When neutrals are formed, these will not be affected by the electric fields and will be measured by a detector located at the end of the straight section (Fig. 1). The ions are typically accelerated to an energy of 22 keV before injection into ELISA. The revolution time in ELISA is for typical molecular ions in the range of 20-200μs.
ELISA operates around 240 days per year and beam can, if necessary, be provided 24 hours per day, 5 days a week. A scientifically trained person is in charge of the daily operation of the ring and assists the user groups in case of practical problems.
An electrospray ion source has also been mounted on an accelerator of a mass separator type (SEPI, Fig.2). The ions produced by the ion source are typically accelerated to a kinetic energy of 50 q keV, where q is the charge state of the ion. The accelerator is equipped with a scattering chamber followed by an electrostatic analyser for analysis of fragments originating from collisions in the scattering chamber. This accelerator is designed for measurements of MIKE (Mass-analysed Ion Kinetic Energy) spectra, which provide information on the distribution of fragment ions. The accelerator is run by the individual experimentalist approximately 200 days per year.
In addition to ELISA and SEPI, IFA (Department of Physics and Astronomy) and ISA (Institute of Storage Ring Facilities) operate other facilities, most notably the storage ring ASTRID / Aarhus Storage Ring Denmark), which is a combined storage ring and a synchrotron radiation facility. The two infrastructures are closely connected both scientifically and technically, and are located in the same building complex. This is of great benefit for users with daily contact to both ISA and IFA staff. On the technical side there is access to the technical infrastructure associated with IFA and ISA. Similarly, expertise is present in many different and specialised areas due to the large research staff of IFA and ISA. The technical infrastructures are diverse, including mechanical as well as electronic workshops and chemistry and biology laboratories. Having an infrastructure integrated into an active university research environment stimulates cross-disciplinary research.
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Figure1
2. Management of the access provided
2.1 During the last years ELISA has been an open facility for access through a Transnational Access Contract. (HPRI-2001-000122). This contract granted access to both storage rings ASTRID and ELISA. ASTRID is now mainly a synchrotron radiation facility and is funded by a new access contract. Concerning the access to the ELISA facility, at present, users demanding access to the facility are submitting a proposal which is reviewed annually by a user selection panel. Prior to this, the potential user group has gained insight into the possibilities with the installation, either through information available on the Internet or by personal contact. A personal contact to local staff is always encouraged, as this interaction is very beneficial for setting up an experimental program. After the approval by the panel, the group is allocated time at the installation in accordance with the user’s own schedule. Typically, a two weeks of beam time is allocated which can be repeated in order to complete the study in question. During the allocated time the user is naturally in charge of the experiment performed, completely independent of any other activity going on. Local staff will assist the user, and new users will be trained and instructed. Furthermore, any upcoming problems will have a high priority, with the assistance of the technical staff and laboratories on site. The proposed Transnational Access will follow the common proposal selection rules defined further below.
The data obtained in a given experiment are usually analysed by the users at their home institution. However, some analysis takes place already during the actual beam time of the experiment. In that case help is provided by available computing facilities and by discussions concerning the interpretation of the actual data. This may continue also after the experiment leading to a collaboration between the involved groups.
2.2 ELISA and SEPI are connected to IFA both scientifically and technically. This has a great benefit for users. On the scientific side there is a strong interaction with the scientific staff of IFA, covering many topics in physics and related fields. There is the possibility to attend colloquia and seminars held at IFA, and there is direct access to a large, well-stocked library and on-line journals. On the technical side there is access to technical infrastructures associated with the Department.
Similarly, expertise is present in many different and specialised areas due to the large research staff of IFA. The technical infrastructures are diverse, including mechanical design and construction offices, mechanical and electronic workshops, thin-film laboratories, as well as wet and dry chemistry laboratories.
In connection to the infrastructure, there is a user room/office with access to computers, kitchen facilities, etc. In addition, the secretarial staff assists with accommodation, etc. A guest house operated by the University of Aarhus can provide rooms for guests at the infrastructure.