1 / 17

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.

bayard
Download Presentation

An experimental limit on neutron mirror-neutron oscillation Ulrich Schmidt

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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)

More Related