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Commissioning Results of the Upgraded Neutralized Drift Compression Experiment (open access)

Commissioning Results of the Upgraded Neutralized Drift Compression Experiment

Recent changes to the NDCX beamline offer the promise of higher charge compressed bunches (>15nC), with correspondingly large intensities (>500kW/cm2), delivered to the target plane for ion-beam driven warm dense matter experiments. We report on commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.
Date: April 30, 2009
Creator: Lidia, S. M.; Roy, P. K.; Seidl, P. A.; Waldron, W. L. & Gilson, E. P.
System: The UNT Digital Library
A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions (open access)

A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions

The synthesis of a cyclen derivative containing four isophthalamide groups (L{sup 1}) is described. The spectroscopic properties of the Ln(III) complexes of L{sup 1} (Ln = Gd, Tb, Yb, Eu) reveal changes of the UV/visible absorption, circular dichroism absorption, luminescence and circularly polarized luminescence properties. It is shown that at least two metal complex species are present in solution, whose relative amounts are pH dependent. When at pH > 8.0, an intense long lived emission is observed (for [L{sup 1}Tb] and [L{sup 1}Yb]) while at pH < 8.0, a weaker, shorter-lived species predominates. Unconventional Ln(III) emitters (Pr, Nd, Sm, Dy and Tm) were sensitized in basic solution, both in the visible and in the near infra-red, to measure the emission of these ions.
Date: April 30, 2009
Creator: D'Aleo, Anthony; Xu, Jide; Do, King; Muller, Gilles & Raymond, Kenneth N.
System: The UNT Digital Library
Fast Correction Optics to Reduce Chromatic Aberrations in Longitudinally Compressed Ion Beams (open access)

Fast Correction Optics to Reduce Chromatic Aberrations in Longitudinally Compressed Ion Beams

Longitudinally compressed ion beam pulses are currently employed in ion-beam based warm dense matter studies [1]. Compression arises from an imposed time-dependent longitudinal velocity ramp followed by drift in a neutralized channel. Chromatic aberrations in the final focusing system arising from this chirp increase the attainable beam spot and reduce the effective fluence on target. We report recent work on fast correction optics that remove the time-dependent beam envelope divergence and minimizes the beam spot on target. We present models of the optical element design and predicted ion beam fluence.
Date: April 30, 2009
Creator: Lidia, S.M.; Lee, E.P.; Ogata, D.; Seidl, P.A.; Waldron, W.L. & Lund, S.M.
System: The UNT Digital Library
FLUOR'S USE OF LEADING INDICATORS - LESSONS, THEORY & PRACTICE (open access)

FLUOR'S USE OF LEADING INDICATORS - LESSONS, THEORY & PRACTICE

None
Date: April 30, 2009
Creator: SS, PREVETTE
System: The UNT Digital Library
Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector (open access)

Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector

Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab's A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infrared laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 50-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.
Date: April 30, 2009
Creator: Ruan, J.; Lumpkin, A. H. & Santucci, J. K.
System: The UNT Digital Library
Linear pi-Acceptor-Templated Dynamic Clipping to Macrobicycles and[2]Rotaxanes (open access)

Linear pi-Acceptor-Templated Dynamic Clipping to Macrobicycles and[2]Rotaxanes

Functional rotaxanes are one of the representative nanoscale molecular machines that have found applications in many areas, including molecular electronics, nanoelectromechanical systems (NEMS), photo controllable smart surfaces, and nanovalves. With the advent of molecular recognition and self-assembly, such molecular compounds can now be obtained efficiently through template-directed synthesis. One of the common strategies of making [2]rotaxanes involves the clipping of a macrocycle around a preformed dumbbell-shaped template in a [1+1] or [2+2] manner. While early examples were based on irreversible kinetic pathway through covalent bond formation, recent advances on reversible dynamic covalent chemistry (DCC) has attracted great attention to this field. By virtue of thermodynamically controlled equilibria, DCC has provided highly efficient and versatile synthetic routes in the selection of specific products from a complex system. Among the several reversible reactions in the category of DCC reactions, the imine formation has proven to be very versatile in macrocyclization to give complex interlocked molecular compounds. Cryptands are three dimensional bicyclic hosts with preorganized cavities capable of inclusion of ions and small molecules. Replacing the nitrogen bridgeheads in common cryptands with aromatic ring systems gives cyclophane-based macrobicycles. The introduction of aromatic ring systems into a preorganized cage-like geometry facilitates ion-{pi} interactions and …
Date: April 30, 2009
Creator: Klivansky, Liana M.; Koshkakaryan, Gayane; Cao, Dennis & Liu, Yi
System: The UNT Digital Library
Neutron Energy Measurements in Radiological Emergency Response Applications (open access)

Neutron Energy Measurements in Radiological Emergency Response Applications

We present significant results in recent advances in the determination of neutron energy. Neutron energy measurements are a small but very significant part of radiological emergency response applications. Mission critical information can be obtained by analyzing the neutron energy given off from radioactive materials. In the case of searching for special nuclear materials, neutron energy information from an unknown source can be of paramount importance.
Date: April 30, 2009
Creator: Sanjoy Mukhopadhyay, Paul Guss, Michael Hornish, Scott Wilde, Tom Stampahar, Michael Reed
System: The UNT Digital Library
OPTIMIZATION STUDIES FOR THE ADVANCED PHOTOINJECTOR EXPERIMENT (APEX) (open access)

OPTIMIZATION STUDIES FOR THE ADVANCED PHOTOINJECTOR EXPERIMENT (APEX)

The Advanced Photoinjector Experiment (APEX) seeks to validate the design of a proposed high-brightness, normal conducting RF photoinjector gun and bunching cavity feeding a superconducting RF linac to produce nC-scale electron bunches with sub-micron normalized emittances at MHz-scale repetition rates. The beamline design seeks to optimize the slice averaged 6D brightness of the beam prior to injection into a high gradient linac for further manipulation and delivery to an FEL undulator. Details of the proposed beamline layout and electron beam dynamics studies are presented.
Date: April 30, 2009
Creator: Lidia, S.M.
System: The UNT Digital Library