Lawrence Livermore National Laboratory Nicholas Scielzo Lawrence Fellow Physics Division, Physical Sciences LLNL-PRES Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 Precise neutrino and neutron spectroscopy using trapped radioactive ions August 8, 2009

2 Lawrence Livermore National Laboratory Ion traps  Efficiently collect any isotope nearly at rest, suspended only by electromagnetic fields  Recoil nucleus momentum available for study  <1mm 3 volume Combine ion-trapping techniques with modern detector technology to perform  -decay and  -delayed neutron decay measurements with unprecedented precision Entire decay kinematics reconstructed to determine energy/momenta of: (1)Neutrinos in beta decay (2)Neutrons in beta-delayed neutron emission  Neutrino escapes detection!  Neutron emission n Spectroscopy of “invisible” and difficult-to-detect particles

3 Lawrence Livermore National Laboratory Scientific goals Nuclear beta-decay correlations Beta-delayed neutron emission Improved decay spectroscopy can address many interesting questions: Existence of new particles influences the correlation between momenta of emitted beta and neutrino particles Large Hadron Collider at CERN 8.6 km ion trap for beta-decay 86 cm Table-top device sensitive to physics at TeV energies! Are there massive particles that have never been observed? Measurements of beta-delayed neutron emission branching ratios and energies are needed to better understand: the distribution of stable nuclei produced by the rapid-neutron capture process (r process) when the exotic nuclei produced decayed back to stability the evolution of nuclear structure in neutron- rich nuclei fission reactor performance SN1987A supernova: r-process site

4 Lawrence Livermore National Laboratory Nuclear  decay d u  W Compare experimental values to SM predictions Put limits on terms “forbidden” by SM Coupling constants: C S, C V, C A, C T

5 Lawrence Livermore National Laboratory The  angular correlation Neutrino too difficult to detect – correlation must be inferred from nuclear recoil Sensitive to detector thresholds and resolution Correlation easily perturbed by scattering  Nuclear recoil Neutrino escapes detection! Example Recoil Energy Spectrum ( 21 Na) a > 0 leads to larger average recoil energy Direct detection – acceleration of daughters Energy shift in subsequent particle emission

6 Lawrence Livermore National Laboratory 8 Li  decay 8 Li 8 Be    t 1/2 =0.84 s        MeV   100% Q  = MeV In most beta decays there are 5 degrees of freedom: 3 × = 5 Of course, 8 Li (and 8 B) decays are not like most beta decays – the excitation energy of the 8 Be daughter is broad, leading to another degree of freedom – the beta-decay Q value. Even still, we can overconstrain the system – by measuring 7 degrees of freedom!   energy, ,    energy sum  the Q value  energy difference  recoil energy, r   r energy/momentum of beta, neutrino, nucleus conservation of energy/momentum

7 Lawrence Livermore National Laboratory Beta-neutrino correlation in 8 Li DSSD Plastic scintillator    8 Li + 8 Li  8 Be*     Neutrino momentum/energy can be determined from   and recoiling 8 Be momentum/energy   momentum/energy measured from DSSD and plastic scintillator detector 8 Be momentum/energy determined from  particle break- up… with no recoil,  particles would have same energy and would be back-to-back. With recoil, energy difference can be up to 730 keV and the angle can deviate by as much as ±7 0 Low mass of 8 Li and Q ≈ 13 MeV lead to large recoil energies of 12 keV which makes the correlation easier to measure. Other  correlation measurements have had to deal with recoil energies of only keV. Beta-neutrino correlation measurement takes advantage of 1 mm 3 trapped ion sample and position and energy resolution of double-sided silicon strip detectors to precisely reconstruct momentum vectors of all emitted particles (including neutrino!)

8 Lawrence Livermore National Laboratory Beta-delayed neutron emission Plastic scintillator  n 94 Sr 95 Rb + 95 Rb  95 Sr*    94 Sr*  n 1-mm 3 trapped-ion sample and 1-ns timing resolution of detectors determines neutron momentum/energy to ~1% from time-of-flight of recoiling daughter ion intrinsic efficiency for MCP detectors can be ~100% many fission fragments available from the newly- developed CARIBU facility (an intense source of fission-fragment beams) at ANL Novel approach: determine neutron energies and branching ratios by detecting beta particles and recoil ions that emerge from ion trap Provide reliable data for: r-process nucleosynthesis, nuclear structure, nuclear reactor performance, modeling of environments where fission fragments are produced MCP ion detector Example Q = 4.9 MeV t 1/2 = sec P n ≈ 9%