ABSTRACT. The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. In the configuration pioneered by the Autofib instrument at the Anglo-Australian Telescope, Hectospec's fiber probes are arranged in a radial "fisherman on the pond" geometry and held in position with small magnets. A pair of high-speed, six-axis robots move the 300 fiber buttons between observing configurations within ∼300 s, and to an accuracy of ∼25 mm. The optical fibers run for 26 m between the MMT's focal surface and the bench spectrograph, operating at . Hectochelle, another high-dispersion bench spectrograph R ∼ 1000-2000 offering , is also available. The system throughput, including all losses in the telescope optics, fibers, R ∼ 35,000 and spectrograph, peaks at ∼10% at the grating blaze in 1Љ FWHM seeing. Correcting for aperture losses at the 1Љ .5 diameter fiber entrance aperture, the system throughput peaks at ∼17%, close to our prediction of 20%. Hectospec has proven to be a workhorse instrument at the MMT. Together, Hectospec and Hectochelle have been scheduled for of the available nights since its commissioning. Hectospec has returned approximately 60,000 1 3 reduced spectra for 16 scientific programs during its first year of operation.
Ag is grown epitaxially on Cu(111) to form quantum wells. The resulting quantum-well states and resonances, observed with angle-resolved photoemission, exhibit shifts in energy for varying emission directions and for changing Ag-film thicknesses. The results are utilized in a determination of the Ag bulk sp-band dispersion relation near the L point in the Brillouin zone. Effective masses and the Fermi surface near the L point are deduced. The Fermi surface agrees well with that obtained earlier from de Haas-van Alphen measurements.
Binospec is a high throughput, 370 to 1000 nm, imaging spectrograph that addresses two adjacent 8ʹ by 15ʹ fields of view. Binospec was commissioned in late 2017 at the f/5 focus of the 6.5m MMT and is now available to all MMT observers. Aperture masks cut from stainless steel with a laser cutter are used to define the entrance apertures that range from 15ʹ long slits to hundreds of 2ʺ slitlets. System throughputs, including the MMT's mirrors and the f/5 wide-field corrector peak at ~30%. Three reflection gratings, duplicated for the two beams, provide resolutions (λ/Δλ) between 1300 and >5000 with a 1ʺ wide slit. Two through-the-mask guiders are used for target acquisition, mask alignment, guiding, and precision offsets. A full-time Shack-Hartmann wave front sensor allows continuous adjustment of primary mirror support forces, telescope collimation and focus. Active flexure control maintains spectrograph alignment and focus under varying gravity and thermal conditions.
The potential benefits (or detriments) of religious beliefs in adolescent and young adults (AYA) are poorly understood. Moreover, the literature gives little guidance to health care teams or to chaplains about assessing and addressing the spiritual needs of AYA receiving hematopoietic stem cell transplants (HSCT). We used an institutional review board-approved, prospective, longitudinal study to explore the use of religion and/or spirituality (R/S) in AYA HSCT recipients and to assess changes in belief during the transplantation experience. We used the qualitative methodology, grounded theory, to gather and analyze data. Twelve AYA recipients were interviewed within 100 days of receiving HSCT and 6 participants were interviewed 1 year after HSCT; the other 6 participants died. Results from the first set of interviews identified 5 major themes: using R/S to address questions of "why me?" and "what will happen to me;" believing God has a reason; using faith practices; and benefitting from spiritual support people. The second set of interviews resulted in 4 major themes: believing God chose me; affirming that my life has a purpose; receiving spiritual encouragement; and experiencing strengthened faith. We learned that AYA patients were utilizing R/S far more than we suspected and that rather than losing faith in the process of HSCT, they reported using R/S to cope with illness and HSCT and to understand their lives as having special purpose. Our data, supported by findings of adult R/S studies, suggest that professionally prepared chaplains should be proactive in asking AYA patients about their understanding and use of faith, and the data can actively help members of the treatment team understand how AYA are using R/S to make meaning, address fear, and inform medical decisions.
The phase shift upon reflection of a valence Bloch electron in Ag at the Ag/Cu(111) interface is determined by angle-resolved photoemission.It shows a singularity at the band edge of Cu, allowing a determination of the substrate band-edge energy. The singular behavior is shown to be a characteristic interfacial property. A simple-model calculation reproduces the main features of the data.One of the key issues involved in the electronic properties of the solid-solid interface is the determination and characterization of the interface potential. This subject of research has attracted considerable interest in recent years. The Schottky-barrier and band-offset problems for systems containing semiconductors are well-known examples. ' Yet from a fundamental point of view, metal-metal interface systems are even more interesting. Due to the rather short screening length in metals, the bands do not bend as in semiconductors; therefore, metal-metal interfaces should provide a simpler environment for the examination of general interfacial properties. These systems also find important applications in superconducting and detector devices. This area of research, however, has been hindered by experimental difficulties. Most techniques for surface studies are not sensitive to an interface buried many atomic layers below the surface, and optical techniques (such as laser spectroscopies) are not suitable due to the opaqueness of metals. The present study is an application of photoemission to deduce the interfacial properties. The system studied here is Ag(111) overlayers grown on Cu(111), a "model" system for which simple theoretical modeling can be easily performed. In this study, the Ag-Cu interface is probed by the valence Bloch electrons in the Ag overlayer in that an incident Bloch electron upon reflection from the interface undergoes a phase shift which is measured experimentally.The phase shift is an important parameter characterizing a scattering potential, and the relation between these is a subject of fundamental interest in quantum scattering problems.The measured phase shift as a function of energy shows a singularity at the band edge of the Cu substrate. The singular behavior is shown to be a general interfacial property; thus, this method will allow an accurate determination of the band-edge energies for a substrate buried beneath an overlayer.The phase shift is determined in photoemission by observing the interference (quantum-well) effects on the Bloch electron wave between the two boundaries of the Ag overlayer. '" The density of occupied states, and hence the photoemission signal, exhibits peaks at energies satisfying the condition of constructive interference. Thus, even though the escape depth of the photoexcited electron is rather short, an interface buried at a large depth below the surface can still be examined easily because the interference effect is inherently a ground-state property. In this sense, the interface is actually probed by the valence Bloch electrons in the Ag overlayer, which then convey th...
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