Because quantum chromodynamics (QCD) is non-perturbative at low energies, strong in- teractions at the ∼ GeV scale are very challenging to understand. Theoretical progress has been made recently using QCD-based effective field theories (EFT). The short-distance physics of the effective theory is absorbed into a limited number of low energy constants (LECs), which are determined by direct experimental measurement. The MuSun experi- ment is measuring the rate Λd for muon capture on the deuteron, which is the simplest weak interaction in a two nucleon system. Λd will be used, in turn, to better determine a funda- mental LEC known as dR in the EFT. An improvement in the precision of this LEC will improve our understanding of several other processes in the two-nucleon sector: pp fusion, the main source of energy in the sun and other main-sequence stars and neutrino-deuteron scattering, as observed in the SNO experiment. The MuSun experiment determines Λd via a precision measurement of the negative muon lifetime in deuterium. The time difference between an incoming muon, which stops in deuterium, and the subsequent decay electron characterizes the muon disappearance rate. That disappearance rate is the sum of the ordinary muon decay rate and the nuclear capture rate. The ultimate goal of the MuSun experiment is to determine the nuclear capture rate (Λd) to a precision of 1.5 %, an order of magnitude improvement over previous efforts. The principal experimental development required to achieve this goal is a cryogenic (T ∼30K) time projection chamber, which not only serves as the deuterium gas target, but also provides an unambiguous measurement of muon stopping position - muons that stop in high Z materials outside the fiducial deuterium volume produce a very large systematic error. The low temperature helps minimize several other systematic errors. The MuSun experiment is taking place at the Paul Scherrer Institut in Villigen, Switzer- land. Over the past 5 years, the MuSun collaboration has staged 4 major experimental production runs. In this thesis, I present a measurement of the muon capture rate on deu- terium, as determined from data taken in the summer of 2013. The estimated statistical and systematic error is about 7.5%.

A series of novel [2]rotaxanes of general formula 1 has been synthesised, exploiting the hydrophobic effect to cause binding inside α- or β-cyclodextrin cavities, and making use of Suzuki coupling to stopper the rotaxane. The size complementarity of the dumbbell and cyclodextrin units was investigated. The rotaxanes were characterised by use of 2D NMR techniques and, in one case, by X-ray crystallography. The reactivity of one such rotaxane (α-cyclodextrin, stilbene core and carboxylic acid stoppered) was investigated by comparison with the corresponding dumbbell. The presence of the cyclodextrin was shown to have a protective influence towards some reactants. The absorption and emission properties of these rotaxanes were compared. We have demonstrated an increase in the fluorescence quantum yield by up to a factor of three. The photo-induced isomerisation of all the stilbene-based rotaxanes and dumbbells synthesised was surveyed; in one case it was found that encapsulation had completely prevented this isomerisation. A quantitative investigation of the proportions and extinction coefficients of the trans and cis isomers of one rotaxane in the photostationary state was undertaken, and the quantum yields of switching deduced. The rate of photodegradation and the ultimate products of this were investigated. The major photoproduct in both cases arose through photo-induced hydration of the stilbene double bond. The final chapter is concerned with attempts to synthesise rotaxanes by reaction of a 1,3,5-triazine with an azo dye (2). Related rotaxanes have been successfully prepared in the past^1-3 , however in this instance the attempts did not result in significant amounts of rotaxane formation. This was rationalised by the shorter length of the dye. The thesis as a whole illustrates the stabilisation of chromophores that is possible through the formation of rotaxanes.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 60-62).

A study of the nuclei Be⁶ , Be⁹ and Cl³³ has been made. These nuclei hare been investigated by observing the neutrons emitted during or after their formation by charged induced reactions. The neutron energies have been measured by the "time of flight" technique, using both the pulsed beams and associated particle methods. The first chapter contains an outline of the Distorted Wave Born Approximation and the application of this theory to the calculation of the angular distributions of neutrons emitted from a (p,n) reaction, which is treated as a special case of inelastic scattering, and also from the single and double stripping reactions (d,n) and (He³, n). In Chapter II is a description of the pulsed beam and associated particle time of flight techniques. A detailed account of the design, construction and mode of operation of the beam pulsing device used for the (p,n) experiments is given. Also included is a description of the neutron detector used together with an account of a method of pulse shape discrimination against gamma rays. The reaction L1⁶(p,n)Be⁶ is reported in Chapter III. The reaction has been studied using the pulsed beam method with proton energies ranging from 7 MeV to 18 MeV. At all incident energies the ground state of Be was excited. For incident energies between 10.0 arid 11.3 MeV there was evidence for an excited state in Be⁶ at 1.7 MeV. Measurements with proton energies between 15.0 and 18.0 MeV confirmed this. The excitation and width of the first excited state has been found to be :-E_x = 1.67 ± 0.05 MeV; Γ = 1.18 ± O.07 MeV. At incident energies of 16.55 and 18.0 MeV evidence has also been found for a second excited state in Be⁶ at an excitation of about 3 MeV. Angular distributions for the ground state neutrons have been measured at incident energies of 8.3, 9.0, 9.6, 10.0, 10.5, 15.0, 16.55 and 18.0 MeV, and for the first excited state at 15.0 MeV. The angular distributions measured at 10.5 MeV and below could be fitted very well by a series of the first three Legendre polynomials, and have been interpreted in terms of compound nucleus theory. It is concluded that for these energies the reaction proceeds through two interfering states in Be⁷ at about 10 MeV excitation with spine of ½⁺ and ³⁄₂^−. An attempt has been made to explain the results obtained at 15.0 MeV and above in terms of a direct reaction theory. The direct reaction theory however gave no semblance of a fit. Calculations have been made in terms of pure phase space considerations in order to explain the nature of the neutron continuum seen in the reaction. It is concluded that the continuum arises chiefly from the four body break-up reaction Li⁶ + p → He⁴ + p + p + n with a small contribution from the reaction Li⁶ + p → Li⁵ + p + n . An experiment performed to study the neutron decay of excited states in Be⁹ populated by the beta decay of Li⁹ is reported in Chapter IV. The neutron energies were measured by the associated particle time of flight technique. It has been found from this experiment that the beta decay of Li⁹ populates not only the ground state and 2.43 MeV state of Be⁹ , but also states at 3.35 and 4.6 MeV. These two states, which have not previously been observed, have been given spin assignments of ½^− and ³⁄₂^−. Assuming that the beta decay branching ratio of Li⁹ to the 2.43 MeV state in Be⁹ is 20 per cent, the branching ratios to the 3.35 and 4.6 MeV states is found to be (7 ± 4) per cent and > 1.5 per cent, compared to shell model predictions of (10 ± 2} per cent and (12 ± 3) per cent. Finally, in Chapter V is reported the reaction P³¹ (Me³, n)Cl³³. This experiment was performed to measure the spin of the first T = ³⁄₂ state in Cl³³ . From the angular distribution of the neutrons, which is characteristic of an L = 0 angular momentum transfer, the spin of the analogue state has been found to be ½⁺. In addition tentative spin assignments of ³⁄₂^+ and ½⁺ have been given to two other states in Cl³³ at 6.30 and 7.45 MeV respectively.

No description available.

No description available.

Results are presented for a unified analysis of the reactions pp → pp, πd → πd and πd → pp over the center-of-mass energy interval from pion threshold to approximately 2.4 GeV. These results for πd → pp and πd elastic scattering are superior to previous VPI analyses of these reactions. In particular, the overall phase in πd → pp has now been determined. Comparisons and predictions are made with previous (separate and unified) analyses of this two-baryon system. Several partial wave amplitudes show resonance-like behavior in these reactions. / Ph. D.

Nosso objetivo e estudar os principais mecanismos de foto absorção no ANTPOT.232 TH entre 7 e 60 Mev, ressonâncias gigantes e mecanismo do quase-deuteron, associados ao decaimento por fissão. Para isso, fizemos medidas da seção de choque de eletrofissão no ANTPOT.232 TH, entre as energias de 7 a 60 Mev, no laboratório do acelerador linear do IFUSP. Utilizamos, na analise, o formalismo dos fótons virtuais, que relaciona a seção de choque de fotofissão a seção de choque de eletrofissão. Foi utilizada a seção de choque de fotofissão medida em livermore e calculamos a seção de choque de fotoabsorção e2 (t=0 e t=1), além da seção de choque de fotoabsorção obtida via quase-deuteron. Verificamos que a contribuição predominante para a seção de choque de eletrofissão e a da componente de dipolo elétrico, sendo as demais contribuições (quadrupolo elétrico e modelo modificado do quase-deuteron) uma ordem de grandeza inferior a esta. / Our objective is to study the main photoabsorption mechanisms in 232T]n between 7 and 60 Mev, namely, Giant Resonances and Quasi-Deuteron, associated to fission decay. We performed electrofission measurements at the linear accelerator of IFUSP. In the analysis, the Virtual Photon Formalism, that relates the photofission cross section to the electrofission cross section, was used. In the calculations, the photofission cross section measured at Livermore Laboratory was used. The E2 photoabsorption and quasi-deuteron photoabsorption cross sections were calculated. We concluded that the most important contribution to the electrofission cross section comes from the El- giant resonance component, the other ones (E2 giant resonance component and quasi-deuteron mechanisms) being 1 or 2% of total electrofission cross section.

Nosso objetivo e estudar os principais mecanismos de foto absorção no ANTPOT.232 TH entre 7 e 60 Mev, ressonâncias gigantes e mecanismo do quase-deuteron, associados ao decaimento por fissão. Para isso, fizemos medidas da seção de choque de eletrofissão no ANTPOT.232 TH, entre as energias de 7 a 60 Mev, no laboratório do acelerador linear do IFUSP. Utilizamos, na analise, o formalismo dos fótons virtuais, que relaciona a seção de choque de fotofissão a seção de choque de eletrofissão. Foi utilizada a seção de choque de fotofissão medida em livermore e calculamos a seção de choque de fotoabsorção e2 (t=0 e t=1), além da seção de choque de fotoabsorção obtida via quase-deuteron. Verificamos que a contribuição predominante para a seção de choque de eletrofissão e a da componente de dipolo elétrico, sendo as demais contribuições (quadrupolo elétrico e modelo modificado do quase-deuteron) uma ordem de grandeza inferior a esta. / Our objective is to study the main photoabsorption mechanisms in 232T]n between 7 and 60 Mev, namely, Giant Resonances and Quasi-Deuteron, associated to fission decay. We performed electrofission measurements at the linear accelerator of IFUSP. In the analysis, the Virtual Photon Formalism, that relates the photofission cross section to the electrofission cross section, was used. In the calculations, the photofission cross section measured at Livermore Laboratory was used. The E2 photoabsorption and quasi-deuteron photoabsorption cross sections were calculated. We concluded that the most important contribution to the electrofission cross section comes from the El- giant resonance component, the other ones (E2 giant resonance component and quasi-deuteron mechanisms) being 1 or 2% of total electrofission cross section.

Introduction Rhenium-186 (t1/2 = 3.72 d) is very attractive for use as a theranostic agent in targeted radionuclide therapy (Eβ max = 1.072 MeV (> 76.6 %); Eγ = 137.2 keV)1. Previously published investigations of high specific activity 186Re production have utilized the 186W(p,n)186Re or 186W(d,2n)186Re reactions2-5. Our group is interested in the refinement and scale-up of the production of high specific activity 186Re by cyclotron irradiations of 186W with deuterons; including investigations of the most suitable target material. WO3 has been successfully used as a target material in proton irradiations by two other groups4,5. Further, the physical properties of WO3, such as the reported monoclinic with Pc space group, body centered cubic crystal structure6 and melting point of 1473 °C, made for an attractive target material as sintered and other more structurally robust pressed pellet target preparations could be explored. Thus, this study reports on the characterization and suitability of WO3 as a full-thickness target material for the deuteron production of 186Re. Materials and Methods Assessments of WO3 for target material suitability and structural integrity were made on thick targets (~1 g) prepared using both commercially available and converted WO3 by either uniaxially pressing (13.8 MPa) of powdered WO3 into an aluminum target support or by placing sintered WO3 pellets (1105 °C for 12 hours) into an aluminum target support. In some experiments, WO3 pellets were prepared by dissolution of Wmetal with H2O2, then treatment with 1.5 M HCl. The recovered hydrated WO3 was calcinated at 800 °C for 4 hours, allowed to cool to ambient temperature, pulverized with a mortar and pestle, uniaxially pressed at 13.8 MPa into pellets with a 13 mm die, and subsequently sintered in a tube furnace under flowing Ar at 1105 °C for 3, 6, and 12 hours. Material characterization and product composition analyses were conducted with SEM, EDS, XRD, Raman spectroscopy, and visible photoluminescence spectroscopy. Thick WO3 targets were irradiated for 10 min at 10 µA with nominal extracted deuteron energies of 17 MeV. Gamma-ray spectroscopy was per-formed to assess production yields and radionuclidic byproducts at least 24 hours post EOB. Results While the color of the commercially available WO3 is slightly different (dull, pale green) than the brighter more yellow color of the chemically processed WO3, X-ray diffraction spectrometry (XRD) indicated the two samples were virtually identical. Attempts to determine how the duration of the sintering process (at 1105 °C) affects the chemical/physical nature of the pellet yielded surprising results. In contrast to the characteristic annealed appearance of sintered material, grains of the WO3 sample appeared more densely packed, but not sintered to one another as had been seen during higher temperature (1550 °C) reductions of WO3 irrespective of the time interval used. Full-thickness pressed or sintered pellets of WO3 were found to disintegrate upon irradiation with the deuteron beam, allowing for the direct irradiation of the aluminum target body producing 24Na as a contaminant. Upon retrieval of the target support it was observed that the WO3 had vaporized, discoloring the surface of the well in the target support and coating the walls of ~61 cm (24 inches) of the terminal portion of the beamline, which then required decontamination. We believe that these observations are the result of outgassing oxygen species that subsequently reacted with the aluminum target support. While these findings are in sharp contrast with the successful production yields and isolations previously reported by both Shigeta et al. and Fassbender et al., we believe that these differences are attributable to differences in target design (previous studies utilized an en-closed target with cooling in front of and behind the target) necessitated by the configuration of our target station. Conclusions. The physical properties of powdered WO3, including its lower melting point and more suitable compressibility than powdered Wmetal, seemed to enhance the structural integrity of a WO3 pellet (whether pressed or sintered). However, when compared to our recent successes with the use of Wmetal based targets, the disappointing degradation of our WO3 targets when irradiated with the incident deuteron beam has led us to believe that Wmetal is the more viable target material for 186Re production in our facility.