121037084
BACKGROUNDS AND THRESHOLD OF XENON10 DARK MATTER EXPERIMENT
118466778
Towards energy resolution at the statistical limit from a negative ion time projection chamber
Abstract We make a proof-of-principle demonstration that improved energy resolution can be obtained in a negative-ion time projection chamber, by individually counting each electron produced by ionizing radiation.
119106969
A coherent understanding of low-energy nuclear recoils in liquid xenon
Liquid xenon detectors such as XENON10 and XENON100 obtain a significant fraction of their sensitivity to light (10 GeV) particle dark matter by looking for nuclear recoils of only a few keV, just above the detector threshold. Yet in this energy regime a correct treatment of the detector threshold and resolution remains unclear. The energy dependence of the scintillation yield of liquid xenon for nuclear recoils also bears heavily on detector sensitivity, yet numerous measurements have not succeeded in obtaining concordant results. In this article we show that the ratio of detected ionization to scintillation can be leveraged to constrain the scintillation yield. We also present a rigorous treatment of liquid xenon detector threshold and energy resolution. Notably, the effective energy resolution differs significantly from a simple Poisson distribution. We conclude with a calculation of dark matter exclusion limits, and show that existing data from liquid xenon detectors strongly constrain recent interpretations of light dark matter.
126147907
The XENON dark matter search experiment
56164482
Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter
We show for the first time that the quenching of electronic excitation from nuclear recoils in liquid xenon is well-described by Lindhard theory, if the nuclear recoil energy is reconstructed using the combined (scintillation and ionization) energy scale proposed by Shutt et al.. We argue for the adoption of this perspective in favor of the existing preference for reconstructing nuclear recoil energy solely from primary scintillation. We show that signal partitioning into scintillation and ionization is well-described by the Thomas-Imel box model. We discuss the implications for liquid xenon detectors aimed at the direct detection of dark matter.
118494907
Importance of upgraded energy reconstruction for direct dark matter searches with liquid xenon detectors
The usual nuclear recoil energy reconstruction employed by liquid xenon dark matter search experiments relies only on the primary scintillation photon signal. Energy reconstruction based on both the photon and electron signals yields a more accurate representation of search results. For a dark matter particle mass m~10 GeV, a nuclear recoil from a scattering event is more likely to be observed in the lower left corner of the typical search box, rather than near the nuclear recoil calibration centroid. In this region of the search box, the actual nuclear recoil energies are smaller than the usual energy scale suggests, by about a factor x2. Recent search results from the XENON100 experiment are discussed in light of these considerations.
17939619
RHIC CRITICAL POINT SEARCH: ASSESSING STARs CAPABILITIES.
In this report we discuss the capabilities and limitations of the STAR detector to search for signatures of the QCD critical point in a low energy scan at RHIC. We find that a RHIC low energy scan will cover a broad region of interest in the nuclear matter phase diagram and that the STAR detector--a detector designed to measure the quantities that will be of interest in this search--will provide new observables and improve on previous measurements in this energy range.
36758350
Highlights from Heavy Ion Collisions at RHIC and the Acoustics of the Little Bangs
At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, heavy nuclei are collided at high energies to create matter that is hot enough and dense enough to dissolve hadrons into a quark-gluon-plasma (QGP). In this lecture, dedicated to the memory of Aditya Sambamurti, I present an introduction to heavy-ion collisions and highlights from the first decade of RHIC results.
125578392
Azimuthal anisotropy of K0(S) and Lambda + anti-Lambda production at mid-rapidity from Au + Au collisions at S(NN)**(1/2) = 130-GeV
17415642
Elliptic Flow: A Study of Space-Momentum Correlations In Relativistic Nuclear Collisions
Here I review measurements of v2, the second component in a Fourier decomposition of the azimuthal dependence of particle production relative to the reaction plane in heavy-ion collisions. v2 is an observable central to the interpretation of the subsequent expansion of heavy-ion collisions. Its large value indicates significant space-momentum correlations, consistent with the rapid expansion of a strongly interacting Quark Gluon Plasma. Data is reviewed for collision energies from sqrt[sNN] = 2 to 200 GeV. Scaling observations and comparisons to hydrodynamic models are discussed.
118058376
Kaon and Lambda Production at Intermediate $p_T$: Insights into the Hadronization of the Bulk Partonic Matter Created in Au+Au Collisions at RHIC
Measurements of identified particles over a broad $p_T$ range may provide strong evidence for the existence of a thermalized partonic state in heavy-ion collisions (\textit{i.e.} a quark-gluon plasma). Of particular interest are the centrality dependence and the azimuthal anisotropy in the yield of baryons and mesons at intermediate $p_T$. The first measurements of $v_2$ and the number-of-binary-collisions scaled centrality ratio $R_{CP}$ for $K_S^0$ and $\Lambda+\bar{\Lambda}$ production in Au+Au collisions at RHIC are presented. These measurements from the STAR detector establish the particle-type dependence of $v_2$ and $R_{CP}$ within $0.4 < p_T < 6.0$. At intermediate $p_T$ (1.5--4.5 GeV/c) $v_2$ of $K_S^0$ and $\Lambda+\bar{\Lambda}$ is shown to follow a number-of-constituent-quark scaling with v_2^{kaon}(p_T/2)/2 = v_2^{lambda}(p_T/3)/3. $R_{CP}$ shows that lambda production at intermediate $p_T$ increases more rapidly with system size than kaon production: consistent with multi-parton dynamics in particle production. At $p_T = 5.5$ GeV/c lambda, kaon, and charged hadron production are suppressed by a similar factor ($R_{CP} \approx 0.33$): establishing the extent of the centrality dependent baryon enhancement. The particle- and $p_T$-dependence of $v_2$, and $R_{CP}$ are consistent with expectations based on hadronization of bulk partonic matter by coalescence. As such, the constituent-quark-number scaled $v_2$ may reflect the anisotropy established in a partonic stage providing strong evidence for the existence of a quark-gluon plasma in Au+Au collisions at RHIC.