Institut für Kernphysik, Forschungszentrum Jülich. Forschungs-Neutronenquelle Heinz- Maier- Leibniz. Max-Planck-Institut für Quantenphysik

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1 Neutron Bound β-decay-bob S. Paul 1, M. Berger 1, R. Emmerich 1, R. Engels 2, T. Faestermann 1, P. Fierlinger 3, M. Gabriel 1, F. Grünauer 1, E. Gutsmiedl 1, F. J. Hartmann 1, R. Hertenberger 4, A. Röhrmoser 5, S. Ruschel 1, J Schön 1, W. Schott 1, U. Schubert 1, A. Trautner 1, T. Udem 6, A. Ulrich 1 1 Physik-Department, TUM 2 Institut für Kernphysik, Forschungszentrum Jülich 3 Excellence Cluster Universe, TUM 4 Sektion Physik, LMU 5 Forschungs-Neutronenquelle Heinz- Maier- Leibniz 6 Max-Planck-Institut für Quantenphysik

2 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

3 1. Principle of BOB With a small predicted branching ratio of the neutron ß decay, the reaction occurs. (L. L. Nemenov, Sov. J. Nucl. Phys. 31 (1980) 115) E kin of hydrogen: ev predicted atomic states: 1s 83.2% 2s 10.4% Correlation between spins of the daughter products delivers new limits on g S and g T

4 1. Principle of BOB forbidden by SM

5 1. Principle of BOB W i (%) for various g S and g T config. i g S =0, g T =0 g S =0.1, g T =0 g S =0, g T =

6 1. Principle of BOB Beyond SM: right handed currents? Left-right symmetric V+A model: In standard model M 1 and M 2 are mass eigenstates of two new vector bosons W L and W R. They couple with left and right handed particles respectively with Ϛ being the mixing angle. Helicity of the neutriono:

7 1. Principle of BOB present values: goal: g S or g T upper limits can be reduced by a factor of 10 Neutrino helicity can be measured within 10-3

8 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

9 energy 2. The metastable 2s state 2s metastable 2p Metastability of the 2s hydrogen atom Ly-alpha: 122nm 1s lifetime manipulation with electric field:

10 energy 2. The metastable 2s state 2s metastable 2p Metastability of the 2s hydrogen atom Ly-alpha: 122nm 1s flight length of 2.5cm lifetime manipulation with electric field: flight length of 20km

11 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

12 3. Planned setup at FRM2

13 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

14 4. Simulations on background simulated hydrogen density Background simulations observable neutrons solid angle hydrogens from decay number of hydrogens At the end of SR6

15 4. Simulations on background Flux of particles without any shielding outside the SR6

16 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

17 5. Mockup experiments General test setup for spin state detection H-2s detection chamber coated with alkali halides such as CsI -> high QE for photo effect. detector efficiency can be in the order of 40%

18 5. Mockup experiments

19 5. Mockup experiments Other detection mode: charge exchange 2s states 1s states

20 5. Mockup experiments Other detection mode: charge exchange

21 Overview 1. Principle of the bound beta decay 2. The metastable 2s state of the H atom 3. Planned setup at FRM2 4. Simulations on background 5. Mockup experiments and options for detection 6. Current status and outlook

22 Status & outlook Step 1 More MC simulations are currently running, including better shielding and more precise geometry of the experiment Cross section measurements for lower energy charge exchange reaction in argon Alternative modes of hydrogen detection such as quenching chamber Installation of first BOB step (confirmation of branching ratio) at FRM2: hopefully until end of 2012! Step 2 Development of a spin conservation field inside the beam tube Using spin filter to analyze the spins of emerging hydrogen atoms Time scale: yet unknown.

23 Thank you for your patience! Questions?

24 Proton source

25 Cesium cell

26 Spin filter spin state selection α states: F,m F >= 1,+1> & F,m F >= 1,0> β states: F,m F >= 1,-1> & F,m F >= 0,0>

27 Spin filter spin state selection

Excitation to kinetic energy transformation in colliding hydrogen and argon atoms

Excitation to kinetic energy transformation in colliding hydrogen and argon atoms March 14, 2014 W. Schott 1, S. Paul 1, M. Berger 1, R. Emmerich 1, R. Engels 2, T. Faestermann 1, P. Fierlinger 3, M. Gabriel