Status of the q n Experiment in Mainz C. Siemensen Institute of Nuclear Chemistry Johannes Gutenberg-University of Mainz International UCN Workshop Mainz, Germany, April 11 th -15 th, 2016 April 13th, 2016 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 1 / 22
ε / q n in the Past ε / q n in the Past 1 Apparatus 2 Fomblin as Horizontal Mirror 3 Charge Measurement 4 Summary and Outlook 5 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 2 / 22
ε / q n in the Past Determination of ε : Charge of the free neutron Scattering using UCN myon neutrinos - electrons "former experiment" (Borisov) Charge of the free neutron Neutral matter Neutrinos of supernova using CN SN1987A (Baumann) ~HV 1 1 https://www.cfa.harvard.edu/sins/datajan2007/sn1987a_wide.tif C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 3 / 22
Apparatus ε / q n in the Past 1 Apparatus 2 Fomblin as Horizontal Mirror 3 Charge Measurement 4 Summary and Outlook 5 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 4 / 22
Apparatus Principle of Measurement optical axis cylindrical mirror deflected beam unpertubed beam force input exit grating grating detector + UCN beam - C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 5 / 22
Apparatus Principle of Measurement optical axis former experiment cylindrical mirror gratings deflected beam electrodes unpertubed beam force input exit grating grating detector detector + UCN beam - cylindrical mirror C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 5 / 22
Apparatus Setup electrode input grating exit gratings cylindrical mirror Fomblin basin C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 6 / 22
1 former exp. 1m former exp.* 1.5m new geometry 1.5m 0.1 UCN 0.01 0.001 0 5 10 15 20 25 30 35 40 45 number of hor. reflections Apparatus Reduction of the Number of Horizontal Reflections former experiment* entrance guide detector & grating cyl. mirror new geometry C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 7 / 22
Apparatus Reduction of the Number of Horizontal Reflections former experiment* entrance guide detector & grating cyl. mirror new geometry 1 Mean reflections: former exp. 1m former exp.* 1.5m former exp. 1 . 0 m : ¯ R ≈ 21 . 7 new geometry 1.5m 0.1 UCN former exp.* 1 . 5 m : ¯ R ≈ 31 . 9 0.01 new geometry 1 . 5 m : ¯ R ≈ 1 . 7 0.001 0 5 10 15 20 25 30 35 40 45 number of hor. reflections C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 7 / 22
Apparatus Automatic Adjustment System gratings: ∆ α ≤ 90 µ rad mirror: ∆ α ≤ 350 µ rad C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 8 / 22
Apparatus Electrode System Without conditioning and cleanroom conditions: E max ≈ 1 . 6 MV m were possible C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 9 / 22
Fomblin as Horizontal Mirror ε / q n in the Past 1 Apparatus 2 Fomblin as Horizontal Mirror 3 Charge Measurement 4 Summary and Outlook 5 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 10 / 22
Fomblin as Horizontal Mirror Fomblin Y-HVAC 140/13 pros cons no solubility in most high viscosity: 1508 cSt 2 detergents dielectric constant dissolved air bubbles pop independent from electric field under vacuum (up to 640 kV / m ) dielectric (moves if ∇ � E � = 0) surface roughness ≈ 5 . 24Å cracks when freezed out 2 Solvay Solexis. Perfluorpolyether - Fomblin Y, M und Z-Öle + Fomblin Fette. 2004 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 11 / 22
Fomblin as Horizontal Mirror Fomblin as Horizontal Mirror 0.06 20kV/m 200kV/m 0.04 404kV/m 579kV/m residuals Δε 640kV/m 0.02 0 -0.02 -0.04 -50 -40 -30 -20 -10 0 T / °C 1 e0 1 e− 1 R/R f 1 e− 2 1 e− 3 1 e− 4 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 q 2 [1/Å ] 2 ambient temperature 0°C − 30°C − 55°C Fit Fit Fit Fit C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 12 / 22
Fomblin as Horizontal Mirror Summary new geometry ⇒ reduction of the number of horizontal reflections prolongated flight path ⇒ doubling of the sensitivity automatic adjustment system ⇒ smaller slit widths improved electrode system ⇒ higher HV-stability liquid Fomblin mirror ⇒ no adjustment required C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 13 / 22
Fomblin as Horizontal Mirror Summary new geometry ⇒ reduction of the number of horizontal reflections prolongated flight path ⇒ doubling of the sensitivity automatic adjustment system ⇒ smaller slit widths improved electrode system ⇒ higher HV-stability liquid Fomblin mirror ⇒ no adjustment required ⇒ δ q n ≈ 1 . 3 · 10 − 21 e √ d level of Baumann obtainable within one day C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 13 / 22
Charge Measurement ε / q n in the Past 1 Apparatus 2 Fomblin as Horizontal Mirror 3 Charge Measurement 4 Summary and Outlook 5 C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 14 / 22
Charge Measurement Charge Measurement C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 15 / 22
Charge Measurement Parameters of the Experiment Beam time 3.11. - 1.12.2014 at UCN, ILL: Parameters: Value: mean flight path t in E-field E ( 0 . 70 ± 0 . 20 ) s n 1 ≈ 19 1 s n 2 ≈ 53 1 s n 3 ≈ 57 1 s n 4 ≈ 40 1 neutron fluxes s electric field ∆ E 1 . 2 MV m gratings 0 . 4 mm slit, 0 . 7 mm spacing slopes ∂ x n 1 = − 6273 1 s · m ∂ x n 2 = − 37173 1 s · m ∂ x n 3 = 45820 1 s · m ∂ x n 4 = 44563 1 s · m τ = 3 . 44 · 10 5 s (approx 4 days) overall measurement time 2 . 4 · 10 − 20 statistical sensitivity e d (3.8 times larger) √ C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 16 / 22
Charge Measurement Modulations of the Count Rate 80 1 70 60 count rate / 1/s Det 2 Det 3 2 50 40 Det 4 AP O 3 30 AP U 20 Det 1 4 6 7 8 9 10 11 12 13 14 15 x / mm C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 17 / 22
Charge Measurement Results 140 90 Det 1 80 120 Det 2 70 frequency 100 Det 3 60 frequency 50 Det 4 80 40 60 30 20 40 10 20 0 0 -3e-18-2e-18-1e-18 0 1e-18 2e-18 3e-18 -200-150-100 -50 0 50 100 150 200 charge q n /e Δx / µm ( 7 . 19 ± 2 . 58 ) · 10 − 6 m ∆ x 1 = ( 5 . 34 ± 0 . 69 ) · 10 − 6 m ∆ x 2 = q n =( − 1 . 82 ± 0 . 24 stat . ± 0 . 09 ∂ x n ... ( 3 . 35 ± 0 . 60 ) · 10 − 6 m ∆ x 3 = ... ± 0 . 02 E ± 0 . 78 t ) · 10 − 19 e ( 4 . 01 ± 0 . 52 ) · 10 − 6 m ∆ x 4 = C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 18 / 22
Charge Measurement Results - Discussion � charge of the free neutron (Baumann, 1987): | ε | ≤ 10 − 21 e � Possible systematic effects: motion of the HV-switch breakdown of the fields optics in E -field Fomblin in E -field C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 19 / 22
Charge Measurement Results - Discussion � charge of the free neutron (Baumann, 1987): | ε | ≤ 10 − 21 e � Possible systematic effects: motion of the HV-switch breakdown of the fields optics in E − field ? ⇒ n ↔ γ in E -field: ∆ x γ ≈ 1 . 8 µ m Fomblin in E − field ? ⇒ distortion by � � U + � � −| U − | ≈ 5 . 2 kV C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 19 / 22
Charge Measurement Results - Discussion � charge of the free neutron (Baumann, 1987): | ε | ≤ 10 − 21 e � Possible systematic effects: motion of the HV-switch breakdown of the fields optics in E − field ? ⇒ n ↔ γ in E -field: ∆ x γ ≈ 1 . 8 µ m Fomblin in E − field ? ⇒ distortion by � U + � � � −| U − | ≈ 5 . 2 kV considering both effects: q n =( − 0 . 32 ± 1 . 22 stat . ± 0 . 39 ∂ x n ± ... ... ± 0 . 10 E ± 0 . 14 t ± 1 . 29 x korr . ) · 10 − 20 e ⇒ q n ≤ 1 . 8 · 10 − 20 e C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 19 / 22
Charge Measurement Effective Tilt of the Horizontal Mirror Electrodes x r 1 d SF ( x ) � ˜ δ eff = Ω( x ) d x x r − x l d x Shielding x l 0.5 surface distortion / µm symmetric − 0 . 04 µ rad δ eff ( symm . ) = 0.4 asymmetric 2,5kV asymmetric 5,0kV 0.3 − 0 . 37 µ rad δ eff ( asymm . 2 . 5kV ) = asymmetric 10kV 0.2 − 0 . 73 µ rad δ eff ( asymm . 5 . 0kV ) = 0.1 Basin − 1 . 28 µ rad δ eff ( asymm . 10kV ) = 0 -4 -2 0 2 4 x / cm ∆ F = ∆ E · q n = g m n sin δα ⇒ δα ≈ 1 . 5 µ rad ⇒ ∆ U ± ≈ 5 . 2 kV C. Siemensen (Kernchemie) Status of the q n Experiment in Mainz April 13th, 2016 20 / 22
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