Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · date | New search

You searched for subject:(Proton size). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


York University

1. Bezginov, Nikita. Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen.

Degree: PhD, Physics And Astronomy, 2020, York University

A high-precision measurement of the transition frequency between the 2S_1/2, f=0 and 2P_1/2, f=1 states in atomic hydrogen is presented. The interval is measured by using a fast beam of hydrogen atoms and a novel method of frequency-offset separated oscillatory fields (FOSOF), an extension of the separated-oscillatory-fields (SOF) method. Our result for the 2S_1/2, f=0-to-2P_1/2, f=1 interval is 909871.7 kHz with the total uncertainty of 3.2 kHz, which is the most precise measurement of this transition to date. The root-mean-squared charge radius of the proton, determined from this measurement, is r_p=0.833(10) fm, in agreement with the proton radius determined from muonic-hydrogen spectroscopy, and 4.2 standard deviations away from the CODATA 2014 recommended value, which is determined entirely using electrons (using hydrogen spectroscopy and electron-proton scattering). Advisors/Committee Members: Hessels, Eric (advisor).

Subjects/Keywords: Physics; Proton; Proton radius; Proton size; Hydrogen; Hydrogen spectroscopy; Spectroscopy; Precision spectroscopy; Proton rms charge radius; Proton radius puzzle; Lamb shift; FOSOF; SOF

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bezginov, N. (2020). Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen. (Doctoral Dissertation). York University. Retrieved from http://hdl.handle.net/10315/37734

Chicago Manual of Style (16th Edition):

Bezginov, Nikita. “Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen.” 2020. Doctoral Dissertation, York University. Accessed November 26, 2020. http://hdl.handle.net/10315/37734.

MLA Handbook (7th Edition):

Bezginov, Nikita. “Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen.” 2020. Web. 26 Nov 2020.

Vancouver:

Bezginov N. Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen. [Internet] [Doctoral dissertation]. York University; 2020. [cited 2020 Nov 26]. Available from: http://hdl.handle.net/10315/37734.

Council of Science Editors:

Bezginov N. Measurement of the 2S1/2, f = 0 2P1/2, f = 1 Transition in Atomic Hydrogen. [Doctoral Dissertation]. York University; 2020. Available from: http://hdl.handle.net/10315/37734


University of Oxford

2. Jones, Christopher A. A micromechanical investigation of proton irradiated oxide dispersion strengthened steels.

Degree: PhD, 2016, University of Oxford

This thesis was most concerned with the mechanical response to irradiation of two in-house produced oxide dispersion strengthened (ODS) steels and two non-ODS coun- terparts. The steels, manufactured by Dr. M. J. Gorley (University of Oxford), were me- chanically alloyed from gas-atomised Fe-14Cr-3W-0.2Ti, with the addition of 0.25Y2O3 powder in the case of the ODS variants. The powders were hot isostatic pressed at consolidation temperatures of 950 °C and 1150 °C. The four steels were designated 14WT 950 (non-ODS), 14YWT 950 (ODS), 14WT 1150 (non-ODS) and 14YWT 1150 (ODS), and were used in the as-produced condition. Initially, the macroscale elastic modulus and yield stress were determined using a four-point flexure test, employing digital image correlation (DIC) as a strain gauge. The microcantilever size eects were then characterised, and it was determined that the yield stress signicantly diverged from macroscale values at microcantilever beam depths of < 4.5 μm. Using knowledge of this, the in-house produced alloys were irradiated with 2 MeV protons at the Surrey Ion Beam Centre (University of Surrey, UK) to a displacement damage of ∼ 0.02 dpa and 0.2 dpa (Bragg peak). This was to produce a deep irradiated layer for the fabrication of large microcantilevers with reduced size effects. The cross-sectional surface of the irradiated layer was then exposed and inclined linear arrays of 250 nm deep indents were placed across the damage prole. 14WT 1150 (non-ODS) revealed a clear proton damage prole in plots of hardness against irradiation depth, 14WT 950 (non-ODS) also showed modest hardening in the region of the Bragg peak. No appreciable hardening was observed in either 14YWT specimens, attributed to the fine dispersion of nanoscale oxides providing a high number density of defect sink sites. However, a large bimodal variation in hardness was measured in both ODS variants. This was investigated using EBSD and EDX, and was determined to be caused by a pronounced heterogeneity of the microstructure. While Hall-Petch strengthening and changes in the local chemistry had some effect on the measured hardness, the most likely cause of the large variation in local hardness was heterogeneity in the nanoscale oxide population. Microcantilevers were fabricated out of the irradiated layer cross-section in 14WT 1150 and 14YWT 1150. Larger microcantilevers, with ∼ 5 μm beam depth, were placed with their beam centre at ∼ 0.026 dpa. Smaller microcantilevers, with ∼ 1.5 μm beam depth, were placed with their beam centre at the Bragg peak, 0.2 dpa. Both the large and the small microcantilevers fabricated in 14WT 1150 (non-ODS) displayed significant irradiation hardening. In the ODS variant, 14YWT 1150, irradiation hardening appeared to be reduced. The work in this thesis successfully showed that it was possible to extract a close approximation of the macroscale yield stress from shallow irradiated layers, providing that the irradiation condition is carefully chosen in…

Subjects/Keywords: 620.1; Micromechanical examination of irradiated layers; Micromecanical testing methods; Lengthscale-dependent crystal plasticity; Micromechanical size effect; Four-point flexure testing; Micromechanical size efffect; Microcantilever; ODS steels; Microcantilever size effect; Proton irradiation; Oxide dispersion strengthened steels; Proton irradiatied layer; Crystal plasticity; Nanoindentation; Four-point bend testing

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jones, C. A. (2016). A micromechanical investigation of proton irradiated oxide dispersion strengthened steels. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:fadd9abf-b5d0-4ea1-9d86-50628ec0476a ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.748672

Chicago Manual of Style (16th Edition):

Jones, Christopher A. “A micromechanical investigation of proton irradiated oxide dispersion strengthened steels.” 2016. Doctoral Dissertation, University of Oxford. Accessed November 26, 2020. http://ora.ox.ac.uk/objects/uuid:fadd9abf-b5d0-4ea1-9d86-50628ec0476a ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.748672.

MLA Handbook (7th Edition):

Jones, Christopher A. “A micromechanical investigation of proton irradiated oxide dispersion strengthened steels.” 2016. Web. 26 Nov 2020.

Vancouver:

Jones CA. A micromechanical investigation of proton irradiated oxide dispersion strengthened steels. [Internet] [Doctoral dissertation]. University of Oxford; 2016. [cited 2020 Nov 26]. Available from: http://ora.ox.ac.uk/objects/uuid:fadd9abf-b5d0-4ea1-9d86-50628ec0476a ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.748672.

Council of Science Editors:

Jones CA. A micromechanical investigation of proton irradiated oxide dispersion strengthened steels. [Doctoral Dissertation]. University of Oxford; 2016. Available from: http://ora.ox.ac.uk/objects/uuid:fadd9abf-b5d0-4ea1-9d86-50628ec0476a ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.748672


Freie Universität Berlin

3. Xu, Chao. Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging.

Degree: 2012, Freie Universität Berlin

Bei der Erforschung des ischämischen Hirninfarktes ist die Differenzierung der ischämischen Penumbra von Infarktkern und angrenzendem gesunden Gewebe von besonderer Relevanz. Mit dem Ziel neue Marker für die Charakterisierung der ischämischen Penumbra zu entwickeln, wurden in dieser Doktorarbeit moderne Verfahren der Magnetresonanztomographie (MRT) angewandt; Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging. Vessel-Size-Imaging ermöglicht die Charakterisierung der Mikrogefäßmorphologie anhand der Mikrogefäßdichte (Q) und der durchschnittlichen Gefäßgröße (VSI). Diese Methode wurde in der vorliegenden Arbeit erstmals bei akuten Schlaganfallpatienten angewandt (n=75). Innerhalb der ersten vierundzwanzig Stunden nach Einsetzen der Symptome konnte ein reduzierter Q-Wert, sowie wie eine Erhöhung des VSI-Wertes im ischämischen Gewebe nachgewiesen werden. In einer Längsschnittmessung von 23 Patienten zeigte sich ein deutlicher Trend, der den Q-Wert als potentiellen Indikator für den Schweregrad der Ischämie ausweist. Des Weiteren wurde beobachtet, dass die mit Gradienten- und Spinecho gemessenen dynamischen Änderungen der transversalen Relaxationsrate schleifenförmig statt reversibel linear verlaufen, wie es aus der Modellierung des VSI zu erwarten war. Die Schleifenform und die Verlaufsrichtung unterschieden sich zwischen gesundem und pathologischem, wie z.B. Tumor- oder ischämischem, Gewebe. Anhand einer Simulation des MRT-Signals in einem Mikroblutgefäßmodel konnte gezeigt werden, dass die Verlaufsrichtung der Schleife hauptsächlich von arteriellem und venösem Blutvolumen, sowie der Verteilung des Kontrastmittels beeinflusst wird. Um Form und Verlauf der Schleife zu bewerten, wurde ein Marker entwickelt, welcher die erzeugte Hyperintensität in Tumor- und ischämischem Gewebe ausnutzt. Dieser neuartige Marker kann in bildgebenden Verfahren verwendet werden, um die Pathologie des zerebrovaskulären Netzwerks zu beschreiben. Das Amid-Proton-Transfer-Imaging (APT) erlaubt die Abschätzung des pH-Wertes in vivo. Bislang waren die klinischen Anwendungsmöglichkeiten auf Grund langer Messzeiten mit hoher Belastung für die Patienten begrenzt. In dieser Arbeit haben wir eine Sequenz entwickelt, welche eine beschleunigte Datenerhebung ermöglicht. Somit konnte die Messung des pH-gewichteten Amid- Proton-Transfer-Verhältniswertes (APTR) erstmals bei Schlaganfallpatienten angewandt werden. Die gemessenen Hypointensitäten des APTR im ischämischen Gewebe und dem akuten Infarkt bestätigten, dass die ischämische Azidose dem finalen Infarkt entspricht. Advisors/Committee Members: w (gender), PD Dr. med. Jochen B. Fiebach (firstReferee), Prof. Dr. rer. nat. habil. Harald E. Möller (furtherReferee), Prof. Dr. rer. nat. Ingolf Sack (furtherReferee).

Subjects/Keywords: Stroke; Magnetic Resonance Imaging; Vessel Size Imaging; Amide Proton Transfer Imaging; Vessel Size; Microvessel Density; pH; 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Xu, C. (2012). Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging. (Thesis). Freie Universität Berlin. Retrieved from http://dx.doi.org/10.17169/refubium-7048

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Xu, Chao. “Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging.” 2012. Thesis, Freie Universität Berlin. Accessed November 26, 2020. http://dx.doi.org/10.17169/refubium-7048.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Xu, Chao. “Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging.” 2012. Web. 26 Nov 2020.

Vancouver:

Xu C. Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging. [Internet] [Thesis]. Freie Universität Berlin; 2012. [cited 2020 Nov 26]. Available from: http://dx.doi.org/10.17169/refubium-7048.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Xu C. Untersuchung neuer Magnetresonanzmarker für ischämische Schlaganfälle zur Anwendung bei Vessel-Size-Imaging und Amide-Proton-Transfer-Imaging. [Thesis]. Freie Universität Berlin; 2012. Available from: http://dx.doi.org/10.17169/refubium-7048

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.