1. 21. October 2004 IDEA DBD Meeting, Heidelberg 150 Nd activities at TUM V. Lazarev 1, E. Nolte 1, L. Oberauer 1, F. Pröbst 2 1 -Technische Universität München, E15 2 -Max Planck-Institut für Physik, München with help of J. Doncev 2, V. Kochurichin 3, L. Nagorna 4, D. Kovalev 5, S. Schönert 6, M. Stark 1 3 -General Physics Institute, Coherent and Nonlinear Optics Department, Russia 4 -Institute for Single Crystals, Ukraine 5 -Technische Universität München, E16 6 -MPI, Heidelberg, Germany

2. 21. October 2004 IDEA DBD Meeting, Heidelberg  emitters A. Staudt A. Faessler 150 Nd: the shortest half-time for neutrinoless  0 decay the second largest Q-value low  2 background

3. 21. October 2004 IDEA DBD Meeting, Heidelberg Tungstates and scintillation Almost all tungstates scintillate. The best known scintillators are: CdWO 4, PbWO 4, CaWO 4 The reason is the structure of WO 4 From: Williams R.T., Y.C. Zhang, Y. Abraham, and N.A.W. Holzwarth Electronic structure of pure and defective PbWO 4, CaWO 4, and CdWO 4 Invited paper presented by R.T. Williams at the SCINT99 conference in Moscow, Aug. 1999

4. 21. October 2004 IDEA DBD Meeting, Heidelberg Crystal scintillators Tungstates are often scintillators: CaWO 4, CdWO 4, PbWO 4 Measurements with CdWO 4 are done with low background: 0.03 counts/(keV kg a) (Danevich F.A. et al. Phys. Rev. C62:044501 (2000)) Crystals of CaWO 4 can have good resolution: 5% at 1332 keV (F. Pröbst) Crystal of Nd 2 (WO 4 ) 3 is probably a scintillator Detector resolution could be With |M 0 | 2 from Staudt,

5. 21. October 2004 IDEA DBD Meeting, Heidelberg Current state of the investigation We need highly enriched neodymium (Russia!): A process of Nd 2 (WO 4 ) 3 growing was investigated. Sample crystals were grown using Czochralski method (V. Kochurichin, Moscow).

6. 21. October 2004 IDEA DBD Meeting, Heidelberg Crystals Successful crystals of CaWO 4

7. 21. October 2004 IDEA DBD Meeting, Heidelberg Current state of the investigation We need highly enriched neodymium (Russia!): A process of Nd 2 (WO 4 ) 3 growing was investigated. Sample crystals were grown using Czochralski method (V. Kochurichin, Moscow). 3 small crystals (about 1 cm 3 each) were delivered to Munich

8. 21. October 2004 IDEA DBD Meeting, Heidelberg Scintillation Jelena Doncev, MPI, München No clear result!

9. 21. October 2004 IDEA DBD Meeting, Heidelberg Spectral characteristics D. Kovalev, TU München, E16

10. 21. October 2004 IDEA DBD Meeting, Heidelberg Current state of the investigation We need highly enriched neodymium (Russia!): A process of Nd 2 (WO 4 ) 3 growing was investigated. Sample crystals were grown using Czochralski method (V. Kochurichin, Moscow). 3 small crystals (about 1 cm 3 each) were delivered to Munich The crystals showed no scintillation (J. Doncev, MPI, D. Kovalev, TUM, E16) A powder of other compositions (e.g. LiNd WO 4 ) showed no roentgen-luminescence (L. Nagorna, Ukraine)

11. 21. October 2004 IDEA DBD Meeting, Heidelberg The choice of a detector Direct countingOther 150 Nd is within detector 150 Nd is outside detector Electron hole pairs (Semiconductors) Production of photons and photoelectrons (Scintillators) Production of phonons (Cryodetectors) Crystal scintillators Liquid scintillators Production of phonons (Cryodetectors)

12. 21. October 2004 IDEA DBD Meeting, Heidelberg Cryogenic detectors Heat capacity of an insulator Heat capacity of a ferromagnet If there is an energy splitting  Energy resolution In case of thermalization Temperature increase Low heat capacity is necessary!

13. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes and the resistance of the thermometer Al-phonon- collector Ir/Au- thermometer Cryodetectors at TUM

14. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes and the resistance of the thermometer Al-phonon- collector Ir/Au- thermometer Cryodetectors at TUM

15. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes and the resistance of the thermometer Al-phonon- collector Ir/Au- thermometer Cryodetectors at TUM

16. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes and the resistance of the thermometer EE cooper- pairs  E prox aluminumIr/Au quasi particles phonon Cryodetectors at TUM

17. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes and the resistance of the thermometer EE cooper- pairs  E prox aluminumIr/Au quasi particles Cryodetectors at TUM

18. 21. October 2004 IDEA DBD Meeting, Heidelberg Particle or light interaction with absorber High frequency phonons are produced Phonons become ballistic and fill the crystal homogeneously In the Al-phonon collector those phonons break up quasiparticles Quasi particles diffuse to the Ir/Au- superconducting thermometer and heat it up Resistance of the film changes -> this is the signal R T Cryodetectors at TUM

19. 21. October 2004 IDEA DBD Meeting, Heidelberg Neodymium cooling NdGaO 3 Thermostat M. Stark, E15, TUM Ir/Au thermometer was glued on the NdGaO 3 crystal Only signals from the thermo- meter were detected Ir/Au thermometer was sputtered on the NdGaO 3 crystal The results are not available yet

20. 21. October 2004 IDEA DBD Meeting, Heidelberg Liquid scintillators A scintillator like CTF could be used PMTs cover about 20% of the solid angle where n pe – number of photoelectrons The energy resolution for CTF Photoelectron yield of the CTF with 100 PMT

21. 21. October 2004 IDEA DBD Meeting, Heidelberg Liquid scintillators With 400 PMT the energy resolution Background at 3.3 MeV Now it is possible to solve about 1 % 0 of Nd (S. Schönert, MPI, Heidelberg)

22. 21. October 2004 IDEA DBD Meeting, Heidelberg Local tasks If we assume that everything is perfect and not additional problem arises 1. Preliminary investigation with natural Nd This is sufficient to prove the results of Klapdor-Kleingrothaus, m=400 meV 2. The second step with enriched Nd This is sufficient to prove the inverse hierarchy

23. 21. October 2004 IDEA DBD Meeting, Heidelberg Summary 150 Nd is one of the most interesting candidates to detect a neutrinoless double beta decay There is no established method to measure this decay Estimations show that it could be possible to build a scintillation detector. However, till now no scintillator with Nd was found. (Maybe because of the properties of Nd). It is possible to cool Nd-crystal at least down to 60 mK. However, no phonon signal could be measured A liquid scnitillator with dissolved 150 Nd is the most promising idea at the moment