A measurement of the reaction 12 C (γ,p γ') has been made with tagged photons in the range 49.47<Eγ <70.24 MeV. The relative population of a triplet of states, (7/2-,1/2+ ,5/2+ ) at Eex ~7 MeV in the residual nucleus 11B, following the reaction 12 C (γ,p) has been made by directly resolving their de--excitation γ-­ray decay to the ground state of 11B. This measurement constitutes the highest resolution ever achieved in determining the excitation function of the residual nucleus after a (γ,p) reaction (~48 keV FWHM at Eex ~7 MeV). Comparison has been made with the data of Kuzin et al., who also measured the relative populations, with a resolution of ~270 keV at Eex ~7 MeV. The 7/2-,state at 6.74 MeV has been observed to be the most strongly excited state of the triplet in agreement with Kuzin et al. Disagreement has been found for the relative strengths of the 1/2 + and 5/2 + states in the triplet. An estimation of the maximum effect of angular correlations, between the ejected proton and de-excitation γ-­ray, has been included in the analysis. This effect increases the disagreement between the 2 measurements.

A prototype ASIC (EFT1) for silicon strip detector instrumentation has been designed and tested. The ASIC design contains the electronics necessary for preamplification, shaping, hit detection, and data readout control. The specific­ ation of the ASIC makes it suitable for charged particle spectroscopy applications with the implementation of multiple channels on a single chip reducing the cost compared to expensive discrete instrumentation. The ASIC contains features which have not been implemented before, or are at least unusual, on integrated instrumentation such as the ability to select two gain ranges, the use of a flat­top shaper to increase integral linearity and a current­ driven discriminator output with adjustable voltage to reduce crosstalk effects on sensitive inputs. The testing performed on the ASIC revealed errors that can be removed in further design of the chip which will be implemented using radiation­hard silicon technology.

A search for new examples of proton emission from ground and low lying states was conducted at Argonne National Laboratory. Of particular interest were examples of proton emission from nuclei which were deformed or had an odd number of neutrons, the majority of known proton emitters being odd-even and near-spherical. Candidate nuclei were created via fusion evaporation, these recoils then being separated according to their mass to charge ratio by the Fragment Mass Analyser, before being implanted into a Double Sided Silicon Strip Detector. Any subsequent alpha or proton decays were then recorded.

The radioactive nucleus ¹³N (t½ = 10 min, Jπ = ½) contains one loosely bound proton (Sp = 1.94 MeV) which can be considered to be bound to a core of ¹²C. Taking advantage of the recent availability of beams of radioactive nuclei at Louvain-la-Neuve, Belgium, a beam of ¹³N has been used to investigate the transfer reaction ¹¹B(¹³N,¹²C)¹²C. Particle-γ coincidence data was taken, using the LEDA silicon strip array and BaF₂ modules, gating on the 15.11 MeV γ-decay from the T = 1 state in ¹²C*. Two final states, corresponding to ¹²Cgs + ¹²C*(15.11 MeV) and ¹²C*(4.44 MeV)+ ¹²C*(15.11 MeV) have been observed and angular distributions have been measured for both transitions at each of two beam energies, 29.5 MeV and 45 MeV. The results are discussed with special reference to the loosely bound nature of the valence proton in ¹³N; the transfer reaction has been modelled using a DWBA code, with the ¹³N ground state constructed as a mixture of states: a p½ proton bound to ¹²Cgs , or a p3/2 proton bound to ¹²C*₂₊ (4.44 MeV). Fits to the experimental data have been obtained using a very shallow set of optical potentials, which are found to be energy dependent. The agreement with experiment is good, with the exception of the ¹²C*(4.44)+¹²C*(15.11) transition at the lower beam energy, which is significantly underestimated by the calculations, suggesting a contribution from a different reaction mechanism.

Thesis (PH.D.) -- Syracuse University, 2004. / "Publication number AAT 3160408."

This thesis outlines the search for neutral Higgs bosons in a mass range of m_H/A = 200 GeV − 1.2 TeV, decaying to a pair of hadronically decaying tau leptons. The search is performed using &radic;s = 13 TeV proton-proton collision data, corresponding to an integrated luminosity of 3.21 fb^-1, recorded by the ATLAS detector. No excess over the predicted Standard Model background is observed and upper limits are placed on the production cross section times branching fraction as a function of the mass of the scalar resonance. When combined with the results of the analysis where one of the tau leptons decays to either a muon or electron, the 95% confidence level upper limit on the cross section times branching fraction ranges from 1.4 pb at m_H/A = 200 GeV to 0.025 pb at m_H/A = 1.2 TeV for a scalar boson produced via gluon-gluon fusion, and 1.6 pb at m_H/A = 200 GeV to 0.028 pb at m_H/A = 1.2 TeV for a scalar boson produced via b-associated production. The results are interpreted in the Minimal Supersymmetric extension to the Standard Model (MSSM) as a limit on the value of tan&beta;, as a function of the mass of the neutral CP-odd MSSM Higgs boson. In the mmod+ scenario, the 95% confidence level upper limit is tan&beta; &LT; 7.6 for m_A = 200 GeV, and tan&beta; &LT; 47 for m_A = 1 TeV. For the mass range m_A &GT; 500 GeV, the upper limit on tan&beta; is improved in comparison to previous ATLAS searches.

An intra-pulse Interaction Point fast feedback system (IPFB) has been designed for the Next Linear Collider (NLC), to correct relative beam-beam misalignments at the Interaction Point (IP). This system will utilise the large beam-beam kick that results from the beam-beam interaction and apply a rapid correction to the beam misalignment at the IP within a single bunch train. A detailed examination of the IPFB system is given, including a discussion of the necessary electronics, and the results of extensive simulations based on the IPFB concept for fast beam correction are presented. A recovery of the nominal luminosity of the NLC is predicted well within the NLC bunch train of 266 ns. The FONT experiment - Feedback On Nanosecond Timescales - was proposed as a direct test of the IPFB concept and was realised at the NLC Test Accelerator at SLAC. As part of FONT, a novel X-band BPM was designed and tested at the NLCTA. The results of these tests with the NLCTA short and long-pulse beam are presented, demonstrating a linear response to the position of the 180 ns long-pulse beam: measurements show a time constant of ~1.5 ns and a precision of better than 20 microns. A novel BPM processor for use at X-band, making use of the difference-over-sum processing technique, is also presented in detail, with results given for both short and long-pulse beams. The FONT design concepts and modification of the IPFB system for use at the NLCTA are described. The design of a fast charge normalisation circuit, to process the difference and sum signals produced by the BPM processor, forming part of the FONT feedback circuit, is detailed extensively. Bench tests of the feedback electronics demonstrate the effectiveness of the normalisation and feedback stages, for which a signal latency of 11 ns was measured. These bench tests also show the correct operation of the normalisation and feedback principles. Finally, the results of a full beam test of the FONT system are presented, during which a system latency of 70 ns was measured. These rigorous tests establish the soundness of the IPFB scheme and show correction of a mis-steered bunch train within the full NLCTA pulse length of 180 ns.