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Article: Performance of a slow positron beam using a hybrid lens design

TitlePerformance of a slow positron beam using a hybrid lens design
Authors
KeywordsFocusing
Hybrid lens
Positron beam
S-parameter imaging
Issue Date2006
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/apsusc
Citation
Applied Surface Science, 2006, v. 252 n. 9, p. 3132-3137 How to Cite?
AbstractThe University of Hong Kong positron beam employs conventional magnetic field transport to the target, but has a special hybrid lens design around the positron moderator that allows the beam to be focused to millimeter spot sizes at the target. The good focusing capabilities of the beam are made possible by extracting work-function positrons from the moderator in a magnetic field free region using a conventional Soa lens thus minimizing beam canonical angular momentum. An Einzel lens is used to focus the positrons into the magnetic funnel at the end of transportation magnetic field while at the same time bringing up the beam energy to the intermediate value of 7.5 keV. The beam is E × B filtered at this intermediate energy. The final beam energy is obtained by floating the Soa-Einzel system, E × B filter and flight tube, and accelerating the positrons just before the target. External beam steering saddle coils fine tune the position, and the magnetic field around the target chamber is adjusted so as to keep one of the beam foci always on the target. The system is fully computer controlled. Variable energy-Doppler broadened annihilation radiation (VEDBAR) data for a GaN sample are shown which demonstrate the performance of the positron beam system.
Persistent Identifierhttp://hdl.handle.net/10722/80796
ISSN
2015 Impact Factor: 3.15
2015 SCImago Journal Rankings: 0.930
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorCheung, CKen_HK
dc.contributor.authorNaik, PSen_HK
dc.contributor.authorBeling, CDen_HK
dc.contributor.authorFung, Sen_HK
dc.contributor.authorWeng, HMen_HK
dc.date.accessioned2010-09-06T08:10:22Z-
dc.date.available2010-09-06T08:10:22Z-
dc.date.issued2006en_HK
dc.identifier.citationApplied Surface Science, 2006, v. 252 n. 9, p. 3132-3137en_HK
dc.identifier.issn0169-4332en_HK
dc.identifier.urihttp://hdl.handle.net/10722/80796-
dc.description.abstractThe University of Hong Kong positron beam employs conventional magnetic field transport to the target, but has a special hybrid lens design around the positron moderator that allows the beam to be focused to millimeter spot sizes at the target. The good focusing capabilities of the beam are made possible by extracting work-function positrons from the moderator in a magnetic field free region using a conventional Soa lens thus minimizing beam canonical angular momentum. An Einzel lens is used to focus the positrons into the magnetic funnel at the end of transportation magnetic field while at the same time bringing up the beam energy to the intermediate value of 7.5 keV. The beam is E × B filtered at this intermediate energy. The final beam energy is obtained by floating the Soa-Einzel system, E × B filter and flight tube, and accelerating the positrons just before the target. External beam steering saddle coils fine tune the position, and the magnetic field around the target chamber is adjusted so as to keep one of the beam foci always on the target. The system is fully computer controlled. Variable energy-Doppler broadened annihilation radiation (VEDBAR) data for a GaN sample are shown which demonstrate the performance of the positron beam system.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/apsuscen_HK
dc.relation.ispartofApplied Surface Scienceen_HK
dc.rightsApplied Surface Science. Copyright © Elsevier BV.en_HK
dc.subjectFocusingen_HK
dc.subjectHybrid lensen_HK
dc.subjectPositron beamen_HK
dc.subjectS-parameter imagingen_HK
dc.titlePerformance of a slow positron beam using a hybrid lens designen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0169-4332&volume=252&spage=3132&epage=3137&date=2006&atitle=Performance+of+a+slow+positron+beam+using+a+hybrid+lens+designen_HK
dc.identifier.emailBeling, CD: cdbeling@hkucc.hku.hken_HK
dc.identifier.emailFung, S: sfung@hku.hken_HK
dc.identifier.authorityBeling, CD=rp00660en_HK
dc.identifier.authorityFung, S=rp00695en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.apsusc.2005.08.111en_HK
dc.identifier.scopuseid_2-s2.0-32644444788en_HK
dc.identifier.hkuros115969en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-32644444788&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume252en_HK
dc.identifier.issue9en_HK
dc.identifier.spage3132en_HK
dc.identifier.epage3137en_HK
dc.identifier.isiWOS:000236021300008-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridCheung, CK=10044144900en_HK
dc.identifier.scopusauthoridNaik, PS=8451851900en_HK
dc.identifier.scopusauthoridBeling, CD=7005864180en_HK
dc.identifier.scopusauthoridFung, S=7201970040en_HK
dc.identifier.scopusauthoridWeng, HM=7102468725en_HK

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