Department of Physics

Accelerator facilities

Summary


Accelerators

K130 Cyclotron
  • Heavy ion accelerator for nuclear physics (research and applications)
  • Installation started in June, 1990
  • First extracted beam 1992
  • Experimental hall ready 1992
  • First experiments 1993
  • Annual use: 6000 - 7500 h/year

Pelletron
  • 1.7 MV Tandem accelerator for materials physics
  • Transported from Espoo, Finland (VTT) in September 2006
  • Commissioning and first experiments 2007

MCC30/15 Cyclotron
  • Accelerator for protons (18 - 30 MeV) and deuterons (9 - 15 MeV)
  • Installation started in August 2009
  • Acceptance tests were finished in April 2010

 

Layout of the Accelerator Laboratory

Laboratory layout

1: K130 cyclotron, 2: Proton line, 3: MARA (under construction), 4: RITU, 5: Nuclear reactions (LSC), 6: RADEF, 7:isotope production area, 8: MCC30/15 cyclotron, 9: IGISOL4, 10: Pelletron.


The K130 Cyclotron and the Accelerator Laboratory


The uniqueness of the accelerator system of the JYFL laboratory is based on the fact that it consists of the isochronous cyclotron equipped with two external electron-cyclotron-resonace (ECR) ion sources and a multicusp light-ion source, which can deliver an exceptionally large variety of heavy- and light-ion beams up to an energy of 130 q2/A MeV. Beams like Ne, Ar and Kr  are easily available from the JYFL cyclotron. Intense beams of various metallic elements have been produced using the special MIVOC-technique developed at JYFL and by a special oven designed for low material consumption. They include elements such as Mg, Si, Fe, Ti, Ca, Cu and Ge. The negative light ion source LIISA is able to provide proton beams to the cyclotron with intensities of the order of a few mA. 

The following picture shows the beam time hours in 1992 - 2011.

Since 1992 the cyclotron has been operated over 86000 hours, and since 1996 each year the beam time hours have exceeded 6000 hours/year.

Facility developments

The major improvement in the performance of the K130 cyclotron was achieved by building a new 14.5 GHz ECR ion source. The new source was completed and commissioned in the first part of year 2000. The intensities of heavy-ion beams from the cyclotron will increase by a factor of 10 for the medium heavy ions and it is possible to accelerate heavier elements (e.g. Xe) which could not be produced with the  6.4 GHz ECR source. The MIVOC method seems to become a mature technology in production of solid ion beams at ECR ion sources worldwide. Its further development aims to increase the number of available elements. The old 6.4 GHz ECR ion source was upgraded in 2001-02. A new upgrade with a new hexapole structure was started in 2004. The source has been in use since 2005.

Presently about 30 percent of the beam time is used with high intensity proton beams. In the future the same trend will continue. Especially in IGISOL experiments and in isotope production the high intensity proton beams are required. Originally the protons were produced in the multi-cusp ion source as positive ions. The source provided several milliamps of single charged ions from which about 1 milliampere could be transported to the cyclotron for acceleration. The acceleration was not the problem but only 60 - 70 percent of the accelerated beam could be extracted out of the cyclotron. The rest of the beam was dumped inside the cyclotron causing vacuum problems, unnecessary thermal load and making inside components highly radioactive limiting the present beam intensities to 10 - 20 microamperes level. The maintenance and service of the machine was also difficult requiring several days to weeks cooling time before access to the cyclotron. Therefore a new method of acceleration was developed. Instead of accelerating positively charged protons one can produce negatively charged hydrogen ions in the  multi-cusp ion source by adding an extra electron to the hydrogen atom. Negative ions can be extracted with 100 percent efficiency from the cyclotron by shooting them in the end of the acceleration trough a thin carbon foil, which will strip electrons from the hydrogen atoms, and  the positively charged protons will immediately bend out from the magnetic field of the cyclotron. Theoretically the H--acceleration should work in K130 cyclotron for up to 70 MeV protons.  The installation of the beam stripper and other modifications needed for the H--project were done in May 2000. A  new multi-cusp ion source for production of negative hygrogen ions was also built in 2000. The first negative ions were accelerated and extracted in August 2000. Proton intensities up to 60 microampreres can now achieved at 30 MeV, and more than 100 microamperes at 45 MeV.

For weekly runs of isotope production several procedures in cyclotron operation has been automated.  By using an automated beam tuning the use of highly skilled technical staff and the tuning time can be minimized.

The control system of the accelerator facility is based on an industrial control system built by Honeywell (former ALTIM Control, Ahlström Oy, Varkaus, Finland). It was bought in 1989 and delivered in 1990. One of the most important criteria in the selection of the control system was its reliability. After 7 years of operation it has proved to fulfill this criterion. It has operated nearly without any single failure making it possible to use semi-trained student operators during the nights and weekends. Also the total costs of the system were lowest if one counts both the hardware and software development costs. In that time of the purchase the system was based on Intel 186 microprocessors, and of course they have since long time been outdated. Therefore the system was partly updated in 1998 with 486 processors and larger memories so that new applications can be added.

Last update in January 2012.