SuperSUN new infrastructure for experiments with ultracold neutrons at ILL

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1 SuperSUN new infrastructure for experiments with ultracold neutrons at ILL Oliver Zimmer DFG 1491 Raitenhaslach, 2 November 2017

2 UCN production in He-II R. Golub, J.M. Pendlebury, PL 53A (1975) 133 capture ( 4 He) = 0 cold neutron beam converter 1 mev (12 K) UCN = P -1 = -1 decay + -1 upscattering + -1 capture + -1 wall losses free neutron dispersion 7 nm -1 (0.9 nm UCN) phonon-roton dispersion of superfluid 4 He q T [K] max [s] need T < K and low-loss walls

3 Source prototypes SUN-1 & SUN-2 ( 2004) window- and gap-less vertical UCN extraction Schmidt-Wellenburg & Zimmer, Cryogenics 46 (2006) 799 Zimmer et al., Phys. Rev. Lett 99 (2007) Zimmer et al., Eur. Phys. J. C 67 (2010) 589 Zimmer et al., Phys. Rev. Lett. 107 (2011) Piegsa et al., Phys. Rev. C 90 (2014) Schmidt-Wellenburg et al., Phys. Rev. C 92 (2015) Leung et al., Phys. Rev. C 93 (2016)

4 Performances of SUN-2 (fomblin-coated converter vessel) accumulated UCN from 4 litres He-II (0.61 K) 220/cm 3 UCN ToF spectra: Open converter v(max) = 5.1 m/s, E = 144 nev 0. E0 5. E 2 1. E E 1 2. E E 1 3. E E 1 4. E E 1 5. E 1 5. E2 5. E2 4. E2 4. E2 3. E2 3. E extraction = 882, E2 2. E2 1. E2 1. E2 0. E0 0. E0 UCN count rate (s -1 ) E0 5. E 2 1. E E 1 2. E E 1 3. E E 1 4. E E 1 5. E s accumulation v(max) = 3.9 m/s, E = 81 nev 0. E0 5. E 2 1. E E 1 2. E E 1 3. E E 1 4. E E 1 5. E 1 3. E2 3. E2 2.5 E2 2.5 E2 2. E2 2. E2 1.5 E2 1.5 E E2 1. E Time (s) 5. E1 0. E0 5. E 2 1. E E 1 2. E E 1 3. E E 1 4. E E 1 5. E 1 5. E1

5 He-II converter with magnetic UCN reflector: SuperSUN L. Babin, E. Lelievre-Berna, E. Bourgeat-Lamy, S. Degenkolb, Y. Gibert, M. Kreuz, M. Thomas, X. Tonon, S. Turc, O. Zimmer Advantages: in-situ UCN polarizer long storage lifetime high saturation UCN density weak dependence of UCN on wall quality

6 Magnetic reflector reduces (for lfs): kinetic energy at wall frequency of wall collisions -> strong reduction of wall losses

7 SuperSUN apparatus Converter volume: 12 litres UCN production rate: 10 5 s -1 (E < 230 nev) UCN saturation number: (2018, fomblin spectrum) ( 2019, polarised, E < 230 nev)

8 SUN-2 3 He cryostat converter cryostat magnetic trap cryostat

9 3 He cryostat 100 l 4 He reservoir 1-K pot with superleaks 3 He circuit converter cryostat He-II converter UCN extraction guide magnetic trap cryostat superconducting octupole 4 He reservoir

10 3 He cryostat delivered converter cryostat being manufactured magnetic trap cryostat ordered, feasibility study underway

11 Gas handling rack synoptic designed and operational states defined for automatization Industrial solution identical to gas handling systems of ILL dilution fridges

12 Implementation at beam H523 at ILL SuperSUN exp. zone

13 Existing Cold Guide H523 Existing cold beam H523: 10 9 n/s over mm 2 0.7% of whole spectrum is useful (single-phonon UCN production from Å) Have to match existing guide (m=1.2) to Ø7 cm converter guide (m=2.5) Boundary conditions: geometrical aperture and 2D divergence Å Work and slide by S. Degenkolb

14 H523 (as simulated using McStas) SuperSUN Instrument Zone space for new guide: ~ 9.7m curved guide H523 (m=1.2, R=800m, mm 2 ) curved/tapered guide H52 (m=2, R=4000m, mm 2 ) Reactor (LD 2 Cold Source) Work and slide by S. Degenkolb

15 General octagon 4 parameters rectangle is a special case (r 1 = r 2 and φ 1 = π 2 φ 2) General rectangle: 2 parameters (one side is fixed by existing guide) Work and slide by S. Degenkolb

16 Adapter Guides (as simulated) rectangle octagon (tapered, m=2.5) 2500 mm / mm* rectangles (tapered, m=2.5) mm 15 cm for bismuth filter *removable rectangles (straight, m=1.2) 1773 mm / 154 mm* Work and slide by S. Degenkolb

17 The Best Octogons r 1 φ 1 φ 2 85% of the available 8.9 Å flux enters the converter and is guided m=2.5 m=3 gives 90% m=2.5 limited by substrate polish r 2 5% lost at converter 10% lost earlier imperfect transport (gaps, etc.) Rectangular trumpet (no octagon) worse compromise between aperture/divergence best: 82% little improvement with higher m Work and slide by S. Degenkolb

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19 Feasibility design studies Call for expressions of interest for flagship experiments Launch Execution phase Detailed design study of He-3 cryostat Order of He-3 cryostat Launch design of neutron guide and exp. Zone Detailed design study of converter cryostat Design study of magnetic trap cryostat Detailed design study of neutron guide and exp. Zone Order of neutron guide Order of converter cryostat and magnetic trap cryostat Order of multipole magnet Modification of H5 casemate Installation of exp. zone for SuperSUN Install neutron guide Install He-3 and converter cryostats in exp. Zone Commissioning without magnetic trapping Production of UCN on white neutron beam Delivery of magnetic trap cryostat and multipole magnet Install multipole magnet and magnetic trap cryostat Commissioning of the complete SuperSUN source Launch of user operation Delivery of He-3 and converter cryostat

20 PanEDM experiment, TUM, ILL, PNPI, RAL,... Cut through the apparatus: Peter Fierlinger can be separated in two independent magnetically shielded rooms

21 Magnetic shields of PanEDM Passive SF: > 6 1 mhz SF of inner shield alone: > 1 mhz, 1μT excitation Peter Fierlinger Outer + inner shield (OSIS) Inner shield (IS) Outer shield (OS) Chamber housing I. Altarev et al., arxiv: I. Altarev et al., arxiv: P. Fierlinger ILL

22 Implementation of PanEDM at H523

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30 Statistical reach of PanEDM (room-t experiment) RT-OSIS scenario expected to control systematics on adequate level SuperSUN stage I SuperSUN stage II UCN density in source 333 cm cm -3 Diluted density 80 cm cm -3 Transfer loss factor Source saturation loss factor 2 2 Polarisation loss factor 2 1 UCN density in cells (at beginning 6.7 cm cm -3 of storage) Volume of EDM double chamber 33.2 l 33.2 l UCNs per chamber Electric field E V/cm V/cm Ramsey fringe visibility UCN storage time T 250 s 250 s UCNs per chamber after T (1/e) Sensitivity per Ramsey run (1 ) ecm ecm Preparation time 150 s 150 s Measurements per day Sensitivity (1 ) per day ecm ecm Sensitivity (1 ) 100 days ecm ecm Limit (90% C.L.) 100 days ecm ecm UCN polariser made of permanent magnets, 1.8 T across guide Robert Paddock Positions for PhD students and a postdoc available