Skip to main content  ∨   Page logos with links to institutions:
Max Planck Society Max Planck Institute for Nuclear Physics University of Heidelberg
Stored and Cooled Ions Division
Max Planck SocietyMax Planck Institute for Nuclear PhysicsUniversity of Heidelberg Stored and Cooled Ions Division
Superordinated navigation: MPIK Homepage  |  Home  |  Deutsch  |  Sitemap  |  Search  |  Contact
Section navigation:

Contact  Contact

Tel.: +49 6221 516-851
Fax: +49 6221 516-852
Postal Address
Max Planck Institute for Nuclear Physics
P.O. Box 10 39 80
69029 Heidelberg
Visitor Address
Max Planck Institute for Nuclear Physics
Saupfercheckweg 1
Building: Gentner lab,
room 134
69117 Heidelberg


FT-ICR Detection System for KATRIN

Motivation and Experimental Set-up

The FT-ICR Penning Trap Detection System (a prototype of a cylindrical three-electrode Penning Trap) in Heidelberg is being developed for KATRIN external Link [1-3]. The KATRIN experiment has been designed to measure the mass of the electron antineutrino directly with a sensitivity of 0.2 eV, one order of magnitude better than the present upper limit. The intended sensitivity will be obtained by analyzing the end-point of the β spectrum from the decay of tritium gas molecules T2 → (3HeT)+ + e- + νe  .

The KATRIN set up [1-4] comprises a gaseous tritium source, a transport section external Link pre-spectrometer, the main spectrometer and the detector. In the main spectrometer the electrons from the decay are guided by a strong magnetic field and analyzed using electrostatic fields. The tritium gas is removed from the system by differential pumping and cryogenic trapping. The formation of ion clusters (T2n+1)+ which decay with different end-points than T2, will prevent unambiguous analysis of the end-point of the tritium decay. Therefore, the knowledge of the concentrations of these ions is essential to evaluate the β spectrum.

FT-ICR detection system at the MPIK in Heidelberg
Figure 1: FT-ICR detection system at the MPIK in Heidelberg - click for bigger version

The best way for a precise determination of these concentrations is the use of Penning traps with FT-ICR detection systems. Actual photos of the set up in MPIK-Heidelberg and the FT-ICR Penning Trap are shown in Figure 1 and 2, respectively. More details can be found in Ref. [4]. These Penning Trap systems will be located in the transport section (see also Fig. 1 of Ref. [4]).

FT-ICR Penning trap
Figure 2: FT-ICR Penning trap - click for bigger version


^ to the top

Recent Results

There are three main results so far [4]. One of them is that the amplitude of the FT-ICR signal was recorded for corresponding νexc frequency for different species. The amplitude of the FT-ICR signal versus excitation frequencies are shown for the He+, H2O+ ions in Fig. 3. The other result is that the FT-ICR signal at νrf = ν+ was recorded for different potentials applied to the end-cap electrodes. Applying a linear fit to the data (see Fig. 5 of Ref.[4] and using the mass value of the interested ion, the magnetic field was obtained. This measurement was done for the He+ and H2O+ ions. The last recent result is that the Penning Trap was dedicated to determine the minimum number of the ions needed to observe an FT-ICR signal at room temperature. For further details, see Ref. [4]. All the measurements were performed at room temperature and all the species (He+, N2+, and H2O+) were identified by exciting the ion motion at their modified cyclotron frequency.

Amplitude of the FT-ICR signal versus excitation frequency
Figure 3: ν+ is the modified cyclotron frequency. Amplitude of the FT-ICR signal versus excitation frequency (νexc) for He+ ions (Top), and for H2O+ ions (Bottom) (Based on Ref.[4])



4.   A broad-band FT-ICR Penning trap system for KATRIN
M.Ubieto-Díaz, D. Rodríguez, S. Lukic, Sz. Nagy, S. Stahl, K. Blaum
Int. J. Mass Spectrom. 288, 1-5 (2009) external Link
3.   Neutrino mass limit from tritium β decay
E.W. Otten and C. Weinheimer
Rep. Prog. Phys. 71, 086201 (2008) external Link
2.   The Q-value of tritium β-decay and the neutrino mass
E.W. Otten, J. Bonn and Ch. Weinheimer
Int. J. Mass Spectrom. 251, 173-178 (2006) external Link
1.   KATRIN Design Report 2004
Report by the KATRIN Collaboration (pdf, 8.97 MB) external Link
FZKA7090 (pdf, 9.33 MB) external Link
NPI ASCR Rez EXP-01/2005