| Zugriffsnummer | 20546 |
| Dokumenttyp | Konferenzartikel in Zeitschrift |
| Sprache | Englisch |
| Titel | SQUID measurements of remanent magnetisation in refillable ³He spin-filter cells (SFC) |
| Autor(in); Institution |
Hutanu, V.; Hahn-Meitner-Institut Berlin, Dep. SF2, Berlin, GERMANY
Rupp, A.; Hahn-Meitner-Institut Berlin, Dep. SF2, Berlin, GERMANY
Sander-Thömmes, Tilmann; 8.2, Biosignale, PTB-Berlin
|
| Quelle/Jahr | Physica B: 397 (2007), 1-2, 185 - 187 |
| ISSN | 0921-4526 |
| DOI | |
| Verlag | Amsterdam: North-Holland Physics Publ. |
| Konferenzangaben | Sixth International Workshop on Polarised Neutrons in Condensed Matter Investiagions (PNCMI), Berlin, 25-28, September, 2006, Germany |
| Freie Schlagworte | SQUID ; Neutron spin-filter cell ; ³He polarisation ; Remanent magnetic moment ; T1 hysteresis |
| Zusammenfassung | A strong influence of external magnetic fields on the relaxation time constant T1 of glass cells serving as reservoirs for polarised 3He, observed for various alkali metal-coated cells made of different glass types, was initially associated with the presence of a large number of ferromagnetic clusters on the glass surface. Later experiments showed the presence of the so-called ‘‘T1 hysteresis’’ phenomenon with a similar distinctiveness also in uncoated cells made of pure synthetic quartz glass. It suggests that the origin of such a relaxation is a macroscopic magnetisation in the bulk of the cell. We present the results of a multi-SQUID system investigation on magnetised and nonmagnetised quartz glass cells, Cs coated as well as bare wall, to be used as neutron spin filters at HMI Berlin. The presence of a macroscopic remanent magnetic moment in the cells after their exposition to external magnetic fields has been experimentally shown. More than 80% of the remanent magnetic moment of the magnetised cells was found to be concentrated in the region of the glass valves. SQUID measurements reveal the existence of some remanent magnetisation in all valve parts and also in the vacuum grease, but most magnetic are the plastic parts and the O-ring. Different valve and sealing types have been compared in order to find the less magnetisable one. |
