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Towards neutrino mass determination by electron capture

Towards neutrino mass determination by electron capture. Yuri Novikov PNPI (St.Petersburg ) and GSI (Darmstadt) Symposium in Milos: May 20, 2008. Agenda. Ideas Experimental base Experimental feasibility First experimental steps Problems NeuMa programme and collaboration.

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Towards neutrino mass determination by electron capture

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  1. Towards neutrino mass determination by electron capture Yuri Novikov PNPI (St.Petersburg)and GSI (Darmstadt) Symposium in Milos: May 20, 2008

  2. Agenda • Ideas • Experimental base • Experimental feasibility • First experimental steps • Problems • NeuMa programme and collaboration Yu. Novikov,Milos – 20.05.08

  3. History of m measurements 163Ho 35S 37Ar & 22Na 163Ho 3H 163Ho 193Pt 3H 3H 187Re 3H 3H 3H Yu. Novikov,Milos – 20.05.08

  4. Do we need to measure the neutrinomass since the antineutrinomass limit is known? Yes ! • To confirm the results taken from tritium measurements (with completely different systematic uncertainties). • To check the conservation of CPT: • mν= mνˉ? significant difference might be expected because of neutrino mass smallness · Yu. Novikov,Milos – 20.05.08

  5. Auger electron Atomic process Nuclear process Electron vacancy N+1 N Z-1 Z Time range start 0 10-18s 10-10s courtesy of J. Khuyagbaatar Yu. Novikov,Milos – 20.05.08

  6. (Z-1,A)g + Bi Z,A Qn (Z-1,A)h The less Qν, the bigger contribution of mn Qe Bi Qe – Bi should be as small as possible Qe < 100 keV (Z-1,A)g En = K + mn = Qe - Bi Qe: (precision ~1 eV) mn < 10 eV En Bi – еlectron binding energy: (precision ~1 eV) smaller En higher contribution of mn General information on the capture energetics (Z,A) + e (Z-1,A)h + En Qn = En + mn = Qe – Bi (Z,A) Courtesy of S. Eliseev Yu. Novikov,Milos – 20.05.08

  7. The best candidate for mν-measurement T1/2=4.57 ky Qε=2.4-2.8 keV Yu. Novikov,Milos – 20.05.08

  8. Ultra-precise mass measurements Yu. Novikov,Milos – 20.05.08

  9. Frans Michel Penning Hans G. Dehmelt end cap Typical frequencies q = e, m = 100 , B = 6 T f- ≈ 1 kHz f+≈ 1 MHz ring electrode Principle of Penning Trap Mass Spectrometry B Cyclotron frequency: • PENNING trap • Strong homogeneous magnetic field • Weak electric 3D quadrupole field q/m (courtesy of K. Blaum) Yu. Novikov,Milos – 20.05.08

  10. High resolution bolometers Yu. Novikov,Milos – 20.05.08

  11. Low temperature micro-calorimeters x-ray Temperature rise upon absorption: thermometer Recovery time: thermal link absorber • Operation at low temperatures (T<100mK): • small heat capacity • large temperature change • small thermal noise thermal bath (courtesy of L. Fleischmann) Yu. Novikov,Milos – 20.05.08

  12. Metallic magnetic calorimeters Energy Magnetic Field B • Very simple theory : • Sensor material consists of magnetic moments only • 2 level systems • Zeeman like energy splitting E = mB • 1.5 eV Energy deposition of 100 keV Number of flips  1011 Change of magnetic moment (courtesy of L. Fleischmann) Yu. Novikov,Milos – 20.05.08

  13. Advantages of cryogenic micro-calorimeters • Very high energy resolution (σE≈ 1 eVfor Е ≈ 1 keV). • Very small internal background due to small detector dimensions(≈ 100 μ). • Due to long pulse rise (≈ 1 μs),all the atomic (molecular) de-excitations, being shorter than ns, are detected. • Small detector dimensions allow the use of a multi-detector system, which avoids pile-up background. Yu. Novikov,Milos – 20.05.08

  14. Simulated calorimetric spectrum of 163Ho→163Dy Yu. Novikov,Milos – 20.05.08

  15. How can we derive the neutrino mass from electron-capture ? Total capture probability for allowed transition: Capture ratios for '2' and '1' atomic levels: , where Wi = Qε - Bi (i = 1,2) η can be determined from – ratio, where Penning trap Calorimeter Calorimeter + Spectroscopy Yu. Novikov,Milos – 20.05.08

  16. Dependence of neutrino mass value on Qe and λM2/λM1 for 163Ho-decay Yu. Novikov,Milos – 20.05.08

  17. Calorimetric spectrum dS/dECand "figure of merit" -is electron binding energy for the hole "h" A. De Rujula and M. Lusignoli Yu. Novikov,Milos – 20.05.08

  18. Shapes for “calorimetric” lines of 163Ho→163Dy for Qε=2580 eV Yu. Novikov,Milos – 20.05.08

  19. "Figure of merit" q for different Qε and m 163Ho→163Dy Yu. Novikov,Milos – 20.05.08

  20. Data acquisition time T for S=20 events at the edge Yu. Novikov,Milos – 20.05.08

  21. Feasibility of the Programme Yu. Novikov,Milos – 20.05.08

  22. Most precise mass measurements worldwide: • performed with Penning traps • stable nuclides • closed systems • detection of the image current (courtesy of S. George) Yu. Novikov,Milos – 20.05.08

  23. Energy resolution Counts / 0.24 eV Counts / 0.12 eV Energy E [keV] Energy E [eV] (courtesy of L. Fleischmann) Yu. Novikov,Milos – 20.05.08

  24. Search for new candidates Yu. Novikov,Milos – 20.05.08

  25. Differences in the neutrino mass determination in β- and EC- processes m < Qec- Bi m < Qβ Yu. Novikov,Milos – 20.05.08

  26. T1/2=444 y 80.725 K 0+ 194Hg Qε=(69±14) keV En=(-12±14) keV 1- 194Au T1/2=4.57 ky T1/2=50 ky 0+ 202Pb En≈(-35±15) keV Qε=(50±15) keV Qε=2.6 keV En≈0.55 keV 15.35 L1 2- 202Tl Candidates with evaluated Qe<100 keV Yu. Novikov,Milos – 20.05.08

  27. Г εε Bi(2) Qεε Bj(1) (Z-1,A) (Z-2,A) (Z,A) Resonant neutrinoless double-capture Yu. Novikov,Milos – 20.05.08

  28. Candidates for resonant neutrinoless double-capture Yu. Novikov,Milos – 20.05.08

  29. First steps in implementation Yu. Novikov,Milos – 20.05.08

  30. First steps implemented • FaNtOME – conception for Facility for Neutrino Oriented Mass Exploration, based on 5-Penning trap spectrometer, has been elaborated at MPI-K (Heidelberg). • Careful analysis of possible pile-up background for 163Ho-decay in the calorimetric spectrum has been performed. • The investigation of calorimetric spectrum of 163Ho, implanted in absorber by irradiation from ISOLDE mass separator at CERN, was started in Genova. • The background for micro-calorimeter was measured in the keV-region. The result 1 event/100 days, obtained in Genova-Uni, opens very promising possibility to implement long-term measurements. • Experiments to search for new candidates for neutrino mass determination by electron capture are prepared at CERN (ISOLTRAP). The runs are scheduled for 2008. Yu. Novikov,Milos – 20.05.08

  31. Problems, which hopefully can be solved • Systematic uncertainty in the Penning trap measurements (can be solved by using of 5 Penning trap system) • Perturbations to spectra and decay rates in the calorimetric absorbers (effect can be measured by using an external source) • Pile-up background (can be measured independently) • Other problems ??????? Yu. Novikov,Milos – 20.05.08

  32. We are eager to overcome forthcoming difficulties, meanwhile the neutrino physics community should be patient to long-term efforts and should be keenly aware that "Rome was not built in a day" Yu. Novikov,Milos – 20.05.08

  33. Conclusions • Absolute neutrino mass measurements by electron capture have two motivations: • to confirm the existing limit for mass taken from the antineutrino • mass measurements (if CPT is conserved), • to check the CPT conservation itself. • To implement this task, a combination of measurements with new generation Penning trap systems and low energy cryogenic micro- calorimeters is proposed. • First steps in the NeuMa project show the feasibility of neutrino mass determination at the level ≤10 eV for electron capture in 163Ho. • We can expect further improvements in the development of ingenious technique, and also in the search for new candidates for precise neutrino mass determination. • The proposed method could also be used to search for neutrinoless resonant double electron capture. Yu. Novikov,Milos – 20.05.08

  34. CollaborationNeuMa • GSI, Darmstadt─(H.-J. Kluge) • MPI-K, Heidelberg ─(K. Blaum) • University, Genoa ─(F. Gatti) • KIP, Uni-Heidelberg ─(C. Enss) • PNPI and University, St.Petersburg ─(Yu. Novikov) • ISOLDE, CERN ─(A. Herlert) • JYFL, Jyväskylä─(J. Äystö) • University, Mainz ─(K. Blaum) Expected cost of NeuMa program is a few M€ Yu. Novikov,Milos – 20.05.08

  35. ν Nuclear Physics High Energy Physics Atomic Physics Astro Physics Particle Physics Fortes Fortuna juvat !!! Yu. Novikov,Milos – 20.05.08

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