Towards neutrino mass determination by electron capture Yuri Novikov PNPI (St.Petersburg) 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 Yu. Novikov, Milos –

History of m measurements 3H3H 35 S 3H3H 3H3H 37 Ar & 22 Na 3H3H 3H3H 163 Ho 193 Pt 163 Ho 3H3H 187 Re 163 Ho Yu. Novikov, Milos –

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

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

General information on the capture energetics (Z-1,A) g (Z-1,A) h (Z,A) + e (Z-1,A) h + E Q = E + m = Q  –  i (Z-1,A) g + B i Q  –  i should be as small as possible Q    keV The less Q ν, the bigger contribution of m (Z,A) QQ BiBi Q Z,A E E   m   Q   i smaller E  higher contribution of m (precision ~1 eV) B i – еlectron binding energy : Q:Q:Q:Q: (precision ~1 eV) m   10 eV Yu. Novikov, Milos – Courtesy of S. Eliseev

The best candidate for m ν - measurement Q ε = keV T 1/2 =4.57 ky Yu. Novikov, Milos –

Ultra-precise mass measurements Yu. Novikov, Milos –

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

Yu. Novikov, Milos – High resolution bolometers

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

B Metallic magnetic calorimeters Magnetic Field Energy 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  Change of magnetic moment Yu. Novikov, Milos – (courtesy of L. Fleischmann)

Advantages of cryogenic micro- calorimeters Very high energy resolution (σ E ≈ 1 eV for 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 –

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

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 W i = Q ε - B i (i = 1,2) η can be determined from – ratio, where Calorimeter Penning trap Calorimeter + Spectroscopy Yu. Novikov, Milos –

Dependence of neutrino mass value on Q  and λ M2 /λ M 1 for 163 Ho-decay Yu. Novikov, Milos –

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

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

"Figure of merit" q for different Q ε and m 163 Ho→ 163 Dy Yu. Novikov, Milos –

Neutrino mass, eV Figure of merit q Rate / sExpected T, days · ·10 5 2·10 4 2· Data acquisition time T for S=20 events at the edge Yu. Novikov, Milos –

Feasibility of the Programme

Most precise mass measurements worldwide: performed with Penning traps stable nuclides closed systems detection of the image current NuclideRelative uncertaintyReference 4 He1.6* R.S. Van Dyck et al., Phys. Rev. Lett. 92 (2004) C 2 H 2 – 14 N 2 7* S. Rainville et al., Science 303 (2004) S5.0* W. Shi et al., Phys. Rev. A 72 (2005) He2.5* T. Fritioff et al., Eur. Phys. J. D 15 (2001) 141. Yu. Novikov, Milos – (courtesy of S. George)

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

Yu. Novikov, Milos – Search for new candidates

Differences in the neutrino mass determination in β - and EC- processes m < Q β m < Q ec - B i Yu. Novikov, Milos –

Candidates with evaluated Q   100 keV Q ε =2.6 keV T 1/2 =4.57 ky E ≈0.55 keV Q ε =(69±14) keV T 1/2 =444 y E =(-12±14) keV 194 Hg Au K 1-1- Q ε =(50±15) keV T 1/2 =50 ky E ≈(-35±15) keV 202 Pb Tl L Electron capture Q ε (keV)MethodGroup 194 Hg→ 194 Au≈35from T 1/2 ISOLDE (1981) 30±40SchottkyESR-GSI (2005) 69±14Evaluation with measured 194 Hg at ISOLTRAP AME (2003) 202 Pb→ 202 Tl55±20X-ray spectroscopyArgon (1954) and AME (2003) 50±15Evaluation with the revised value for Q ε =35±25 keV of Yale (1971) AME (2003) Yu. Novikov, Milos –

Resonant neutrinoless double-capture (Z,A) (Z-1,A) (Z-2,A) Г εε Q εε B i (2) B j (1) Yu. Novikov, Milos –

Candidates for resonant neutrinoless double-capture εε- transitionQ εε (keV)E=Eγ+B 1 +B 2 (keV)Δ=Q εε -E (keV)First prediction 74 Se+ 74 Ge1209.7(6) (1)(γ+L 1 +L 2 )2.6±0.6D. Frekers (2005) 112 Sn+ 112 Gd1919(4)1925.6(2)(γ+K+K)-6.6±4.0J. Bernabeu et al., (1983) 152 Gd+ 152 Sn54.6(12)56.26(K+L 1 ) 54.28(L 1 +K) -1.6± ±1.20 Z. Sujkowski and S. Wycech (2004) 154 Er+ 154 Dy23.7(21)19.01(L 1 +L 1 )4.7±2.1“—————” Yu. Novikov, Milos –

First steps in implementation

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).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 163 Ho-decay in the calorimetric spectrum has been performed.Careful analysis of possible pile-up background for 163 Ho-decay in the calorimetric spectrum has been performed. 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.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.Experiments to search for new candidates for neutrino mass determination by electron capture are prepared at CERN (ISOLTRAP). The runs are scheduled for Yu. Novikov, Milos – The investigation of calorimetric spectrum of 163 Ho, implanted in absorber by irradiation from ISOLDE mass separator at CERN, was started in Genova.The investigation of calorimetric spectrum of 163 Ho, implanted in absorber by irradiation from ISOLDE mass separator at CERN, was started in Genova.

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

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 –

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 163 Ho. 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.

Collaboration NeuMa GSI, DarmstadtGSI, 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 –

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