The neutron EDM: exp. vs theory Proposed limits on dn  (10-28) e·cm

Präsentation zum Thema: "The neutron EDM: exp. vs theory Proposed limits on dn  (10-28) e·cm"—  Präsentation transkript:

1 The neutron EDM: exp. vs theory Proposed limits on dn  (10-28) e·cm
Progress at  order of magnitude per decade Standard Model out of reach strong contrains on e.g. Super Symmetry  Proposed limits on dn  (10-28) e·cm C.A.Baker et al., dn < 310-26 ecm (90% CL)

2 Schema des EDM- Nachweises
B E - +   Polarisator Analysator B0 E RF-Spule RF-Spule Ww.-Zone freie Präzession Ww.-Zone

3 Ramsey’s Technique

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6 Ein in Richtung B ausgerichteter Kernspin
„Spitze“ des Spin-Vektors Einstrahlen eines resonanten HF-Pulses: …Auslenkung aus der Magnetfeldachse ( z-Achse ) :

7 2. Kernspin bei „90° Puls“ Ein „90°-Puls“ senkrecht zur B0 startet die Präzession

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11 Ramsey-Resonanzkurve am nEDM Experiment (ILL-Grenoble)

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14 Apparatus HV E = 7 kV/cm Neutron storage chamber B-field coils
B = 1  T Hg co-magnetometer Neutron EDM result dn < 310-26 ecm

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16 Role of magnetometry in neutron EDM experiments
● sensitivity of magnetometer much higher than neutron EDM magnetometer → trace systematics ● magnetometer should „see“ same magnetic field → quality of normalization ● no induced false EDM signals Reading light beam Bo E UCN Hg T2  100 s n Hg Sensitivity per batch cycle: 200 fT Sensitivity of neutron EDM magnetometer: 800 fT K. Green et al., NIM A 404 (1998)381

17 statistically limited !!!
Angenommen das Neutron hätte die Größe der Erde... Sensitivity figure dN < 310-26 e cm x  1m at present: visibility:   0.5 ( neutron polarisation ) electric field: E 7 kV/cm ( limited by Hg co–magnetometer ) storage time : T = 130 s ( limited by T2 of Hg co-magnetometer ) Nucn/batch : N  ( ucn 1 cm UCN density !!! ) 1 day of data (  360 Ramsey-cycles ) : 1 year of data ( 250 days ) : statistically limited !!!

18 B E nEDM Experiment am PNPI Gatchina UCN
( I.S. Altarev et al., Phys. At. Nucl. 59 ( 1996 )1152 ) UCN B E

19 Isolatorringe aus Glaskeramik ( Sitall )

20 Prinzipskizze des 3He-Magnetometers
  B Vakuumkammer Cs-Magnetometer 3He magnetometer UCN Leiter Shutter UCN Doppelkammer Ventile Magn. Abschirmung Kompressor 3He Vorratszelle 3He opt. Pumpzelle 3He Reservoir

21 n2EDM PSI – Skizze des Gesamtaufbaus