Polarization Issues in Run 2008

Ahrens, L.; Huang, H.; Zeno, K.

doi:10.2172/939984

Cited by 4 publications

(9 citation statements)

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“…With more Booster scraping, the RHIC emittance tends to be smaller. This has been observed in RHIC proton runs, say, 2006, 2009, 2011, and 2012 [1][2][3][4].…”

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 74%

“…Despite many factors between the Booster to RHIC store, for example, the Booster to AGS transfer (BtA), the AGS ramping, the AGS to RHIC transfer (AtR), and the RHIC ramping and β squeezing, striking correlations of the Booster scraping ratio and RHIC polarization has been presented in 100 GeV polarized proton runs 2006,2008,2009 [1][2][3][4]. This correlation is similarly presented in 250/255 GeV runs.…”

Section: Rhic Polarization Improvementmentioning

confidence: 99%

“…In [1][2][3][4], detailed study of the Booster scraping effect on RHIC polarization is presented for 100 GeV polarized proton run 2006, 2008, and 2009. In the successful run 2006, the Booster input intensity is raised to > 5 × 10 11 , allowing high Booster scraping ratio, up to 2.8.…”

Section: Rhic Polarization Improvementmentioning

confidence: 99%

“…One possible reason is that during that period, a part of the Booster scraping is used for horizontal, and it is known that the vertical scraping is more effective in polarization improvement [1][2][3].…”

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 99%

“…The dependence of the RHIC transverse emittance on the Booster scraping has been presented in [1][2][3] for 100 GeV run 2006 and run 2009. In run 2009, since the Booster input intensity is limited at 4 × 10 11 , with the higher RHIC intensity, the Booster scraping has to be reduced, which resulted in larger transverse emittance.…”

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 99%

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RHIC Proton Luminosity and Polarization Improvement

Zhang

2014

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The RHIC proton beam polarization can be improved by raising the Booster scraping, which also helps to reduce the RHIC transverse emittance, and therefore to improve the luminosity. By doing this, the beam-beam effect would be enhanced. Currently, the RHIC working point is constrained between 2/3 and 7/10, the 2/3 resonance would affect intensity and luminosity lifetime, and the working point close to 7/10 would enhance polarization decay in store. Run 2013 shows that average polarization decay is merely 1.8% in 8 hours, and most fills have the luminosity lifetime better than 14 hours, which is not a problem. Therefore, even without beambeam correction, there is room to improve for RHIC polarization and luminosity. The key to push the Booster scraping is to raise the Booster input intensity, for that two approaches can be used. The first is to extend the LINAC tank 9 pulse width, which has been successfully applied in run 2006. The second is to raise the source temperature, which has been successfully applied in run 2006 and run 2012.

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“…With more Booster scraping, the RHIC emittance tends to be smaller. This has been observed in RHIC proton runs, say, 2006, 2009, 2011, and 2012 [1][2][3][4].…”

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 74%

Section: Rhic Polarization Improvementmentioning

confidence: 99%

Section: Rhic Polarization Improvementmentioning

confidence: 99%

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 99%

Section: Rhic Transverse Emittance Improvementmentioning

confidence: 99%

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RHIC Proton Luminosity and Polarization Improvement

Zhang

2014

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Influence of water on clumped-isotope bond reordering kinetics in calcite

Brenner

Passey

Stolper

2018

Geochimica et Cosmochimica Acta

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Oxygen self-diffusion in calcite and many other minerals is considerably faster under wet conditions relative to dry conditions. Here we investigate whether this "water effect" also holds true for solid-state isotope exchange reactions that alter the abundance of carbonate groups with multiple rare isotopes ('clumped' isotope groups) via the process of solid-state bond reordering. We present clumped-isotope reordering rates for optical calcite heated under wet, high-pressure (100 MPa) conditions. We observe only modest increases in reordering rates under such conditions compared with rates for the same material reacted in dry CO2 under low-pressure conditions. Activation energies under wet, high-pressure conditions are indistinguishable from those for dry, low-pressure conditions, while rate constants are resolvably higher (up to ∼3 times) for wet, high-pressure relative to dry, low-pressure conditions in most of our interpretations of experimental results. This contrasts with the water effect for oxygen self-diffusion in calcite, which is associated with lower activation energies, and diffusion coefficients that are ≥10 3 times higher compared with dry (pure CO2) conditions in the temperature range of this study (385-450 °C). The water effect for clumped-isotopes leads to calculated apparent equilibrium temperatures ("blocking temperatures") for typical geological cooling rates that are only a few degrees higher than those for dry conditions, while O self-diffusion blocking temperatures in calcite grains are ∼150-200 °C lower in wet conditions compared with dry conditions. Since clumped-isotope reordering is a distributed process that occurs throughout the mineral volume, our clumped-isotope results support the suggestion of Labotka et al. (2011) that the water effect in calcite does not involve major changes in bulk (volume) diffusivity, but rather is primarily a surface phenomenon that facilitates oxygen exchange between the calcite surface and external fluids. We explore the mechanism(s) by which clumped isotope reordering rates may be modestly increased under wet, high-pressure conditions, including changes in defect concentrations in the near surface environment due to reactions at the water-mineral interface, and lattice deformation resulting from pressurization of samples. 

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