1. Environment of the nEDM experiment at PSI Jochen Krempel Institute for Particle Physics ETH Zürich 05.11.2014, Ascona1

2. J. Krempel, Institute for Particle Physics, ETHZ Outline External environment constraints Apparatus Thermal stabilization Active magnetic shield Passive magnetic shield B0 current source High Voltage 05.11.2014, Ascona2

3. J. Krempel, Institute for Particle Physics, ETHZ Area map 05.11.2014, Ascona3 nEDM (mu-metal) UCN-source Iron + heavy concrete Private street SULTAN / EDIPO Superconductor test facility 12T COMET Cyclotron for proton therapy Experimental hall (thermal gradients; daily & seasonal changes) COBRA

4. J. Krempel, Institute for Particle Physics, ETHZ Overview nEDM setup 05.11.2014, Ascona4

5. J. Krempel, Institute for Particle Physics, ETHZ Selected modifications since RAL/Sussex/ILL Thermo-house Surrounding Field Compensation (SFC) Super Conducting Magnet Spin flipper/analyser below switch o + lower height over guide o - slits in volume o + better vacuum pumping Degaussing improved More trim coils – now 30+7 (before 8+x) More and better magnetometers (spatial + high bandwidth) See Georg Bison this afternoon and posters of Samer Afach, Malgorzata Kasprzak, Yoann Kermaidic, Hans- Christian Koch, Sybille Komposch, Michal Rawlik, Elise Wursten 05.11.2014, Ascona5

6. J. Krempel, Institute for Particle Physics, ETHZ Thermo-house wooden construction (non magnetic) – thermal stability, acoustical noise, dust protection top floor: experiment lower floor: DAQ + control room – Individual air condition – Floors can be separated (up to now we did not - for simplified access) mounted separated from experiment – (avoid vibration coupling) performance will come later 05.11.2014, Ascona6

7. J. Krempel, Institute for Particle Physics, ETHZ SFC - part I 6 rectangular coils 6m * 8m, 20 windings 10 x 3 axis Fluxgate sensors earth field compensation / sultan field compensation gradient compensation not yet fully possible (lack of number of coils) static stabilisation over time – Pair wise – using inverse matrix  Sensor selection 05.11.2014, Ascona7

8. J. Krempel, Institute for Particle Physics, ETHZ SFC – part 2 Use many (18.. 24) sensors Pseudo inverse matrix Tikhonov regularization 05.11.2014, Ascona8 Afach et al., J. Appl. Phys. 116, 084510 (2014)

9. J. Krempel, Institute for Particle Physics, ETHZ SFC – part 3 >5x shielding 5.. 5000 s of real perturbations 05.11.2014, Ascona9 Improve short time (5Hz) Add coils Afach et al., J. Appl. Phys. 116, 084510 (2014)

10. J. Krempel, Institute for Particle Physics, ETHZ Degaussing / Idealization 05.11.2014, Ascona10 By Allard Schnabel

11. J. Krempel, Institute for Particle Physics, ETHZ Degaussing vs Temperature 1 05.11.2014, Ascona11

12. J. Krempel, Institute for Particle Physics, ETHZ Degaussing vs Temperature 2 05.11.2014, Ascona12 0.02K  0.15Hz  40 pT +2000pT/K (upper limit)

13. J. Krempel, Institute for Particle Physics, ETHZ Mu-metal vs Temperature 05.11.2014, Ascona13 0.2K  0.06Hz  20 pT +100pT/K (lower limit) -Mu of mu-metal (flux return) -Seebeck effect

14. J. Krempel, Institute for Particle Physics, ETHZ B vs Temperature 05.11.2014, Ascona14 By Elise Wursten Sun 07.09.2014 8h30 - Tue, 09.09.2014 9h30 0.3 air 0.4 outside (no air conditioning) 0.7 vacuum tank 1.0 mu-metal 2 nd layer 0.15K  70 pT +500pT/K Air flux of air condition will be optimised soon.

15. J. Krempel, Institute for Particle Physics, ETHZ B0 current source 05.11.2014, Ascona15 2006 - 2011 Since 1012 1s 10^4s 0.1pT 1pT Current measurement certainly at its limit Indication from Cesium sensors that current source might be limiting

16. J. Krempel, Institute for Particle Physics, ETHZ Effect on nEDM-sensitivity Despite all instabilities: we are happy, If “happy” := χ 2 of corrected Ramsey fit is close to 1  good understanding/measurement of magnetic field 05.11.2014, Ascona16

17. J. Krempel, Institute for Particle Physics, ETHZ High Voltage +/- 200kV bipolar HV-supply (FUG) Learning process Cs-fibres Measure leakage current (in ground electrode) – Diode as spark protection (shortcut everything above 5V) – 10^9 ohm (10nA -> 10V) Femto amplifiers (modified) + standard ADC – Typically below 2 nA – 50Hz issue temporarily solved by heavy averaging 05.11.2014, Ascona17

18. J. Krempel, Institute for Particle Physics, ETHZ Source: PrimeEvil at de.wikipedia Technical aspect USB -> optical RS232 or optical Ethernet (TCP/IP) – more robust (against electrical noise [sparks!]) – scalable (multiple devices on one computer) – easier to modularize  better simulation / debugging possibilities 05.11.2014, Ascona18

19. J. Krempel, Institute for Particle Physics, ETHZ 05.11.2014, Ascona19 Thank you for your attention The project is partially funded by the SNF under grant numbers 200021 138211 and 200021 149211.