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An experimental limit on neutron mirror-neutron oscillation Ulrich Schmidt

An experimental limit on neutron mirror-neutron oscillation Ulrich Schmidt Physikalisches Institut, Universität Heidelberg, Germany. What are mirror particles ???. P. World is not P symmetric. P. World is P R symmetric. R. R.

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An experimental limit on neutron mirror-neutron oscillation Ulrich Schmidt

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  1. An experimental limit on neutron mirror-neutron oscillation Ulrich Schmidt Physikalisches Institut, Universität Heidelberg, Germany

  2. What are mirror particles ??? P World is notP symmetric P World is PR symmetric R R

  3. Possible interaction between particles and mirror particles: Oscillations/mixing between neutral particles and mirror particles Properties of mirror particles For each particle exists a mirror particle which has exactly the same properties in the mirror world, as the particle in the world beside handedness. Interaction between particles and mirror particles: gravity

  4. with free flying neutron: only magnetic field counts for DE phenomenology of oscillation

  5. magnetic field strongly suppress oscillation “field free” region

  6. Reappearance experiment beam dump n beam detector field free region field free region

  7. Disappearance experiment n beam detector principle of our measurement:measuring loss of neutrons due to field free region But !! Only is suppressed by a moderate magnetic field (0.1 mT) R ± DR is compatible with 1 => Problem: loss of neutrons due to b-decay, scattering ...

  8. RESEDA am FRM II

  9. Conventionel (3He-counters): < 10kHz/cm2CASCADE: up to 10 MHz /cm2 Problem:n-counting at very high rates CASCADE: Multiple Boron Layers on GEMs 10B + n 7Li +  + 2.79 MeV ( 6%) 3838 b 7Li*+  + 2.31 MeV (94%) • GEMs can be operated to be transparent for charges!  they can be cascaded! • Each one can carry two Boron layers. • Last one operated as amplifier. Accumulate single layer detection efficiency up to 50% for thermal neutrons (1.8Å) and up to 75% for cold neutrons (5Å).

  10. The Gas Electron Multiplier (GEM) Electrons Ions Amplifier Mode • In hole high fields allow Gas amplification 1 - 400 pictures from Sauli Transparent Mode • At gain 1, electric fields transport charges through the holes The GEM inherently introduces high rates capability of 10 MHz/cm2 ! taken from Sauli et al.: http://www.cern.ch/GDD

  11. 1.75 1.5 1.25 1 U. KinkelZ.Phys.C 54 ,573-575(1992) residual magneticfield [µT] 0.75 0.5 0.25 0 0 1 2 3 4 5 6 neutron flight path [m] B-field integralalong neutron flight path length flight path velocity of neutrons gyromagnetic ratio

  12. length flight path: 6m , l = 11Å => v = 360m/s => t = 17ms 2 day measurement, about 105 individual ratios R measuring cycle:- 0.5s without magnetic field- switch magnetic field on, wait 0.1 s- 0.5s with magnetic field- switch magnetic field off, wait 0.1 s

  13. => sensitivity is limited by intensity fluctuations of the beam 3 - 12 0 1 10 8 6 relative error single ratio 4 2 1 2 5 10 20 50 100 correlation time [s] scattering (standard deviation) of the individual ratios: 0.0082 error of the individual ratios calculated from number of count: 0.0039

  14. noise of R~will be much less than noise of R field free region VCN beam detector 50% monitor counter

  15. n Experiment FRM II Barbara Böhm1 Wolfgang Häusler 2 Dominik Streibel 2 CASCADE detector Martin Klein1 Gerd Mozel 1 Jörg Betz 1 Stefan Backfisch 1 1 Physikalisches Institut Heidelberg2 FRM II (Forschungsreaktor München II) Thank youfor your attention

  16. The Assembled 2D-Detector Power supply and thermal management EMI shielding (500 µm Al) Detector entrance window (100 µm Al) FPGA based readout board ASIC frontend-electronic GEM-foils coated with 10B and 2D readout structure

  17. Neutron-Pictures with the 2D-200 CASCADE Detector System old PC-Mouse Water Flow-Controller Tesa-Tape measured at instrument EKN at FZ Jülich Pixel (1.56mm) Pixel (1.56mm)

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