Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration

Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (p_T), elliptic flow, two-particle correlations, non-statistical fluctuations, and suppression of particle production at high p_T. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted to Nuclear Physics A as a regular article; v3 has minor changes in response to referee comments. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Heavy element production in a compact object merger observed by JWST

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GW)2 and likely production sites for heavy element nucleosynthesis via rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright gamma-ray burst GRB 230307A. We show that GRB 230307A belongs to the class of long-duration gamma-ray bursts associated with compact object mergers4–6, and contains a kilonova similar to AT2017gfo, associated with the gravitational-wave merger GW1708177–12. We obtained James Webb Space Telescope mid-infrared (mid-IR) imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns which we interpret as tellurium (atomic mass A=130), and a very red source, emitting most of its light in the mid-IR due to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy element nucleosynthesis across the Universe

Rotating Michelson-Morley experiment based on a dual cavity cryogenic sapphire oscillator

Recent experiments based on cryogenic microwave oscillators [1,2,3] have tested the isotropy of the speed of light (Michelson-Morley experiment) at sensitivities of the order of a part in 1015, which is a similar sensitivity to other best tests [4,5]. Further improvements of the accuracy in this type of experiment are not expected due to the already long data set and the systematic error limit [3]. We have constructed a new rotating Michelson-Morley experiment consisting of two cylindrical cryogenic sapphire resonators. The temperature of the dual cavity is controlled at approximately 6 K where the beat frequency between two oscillators is independent on temperature. By rotating the experiment an improvement of several orders of magnitude in our sensitivity to light speed anisotropy is expected, as the relevant time variations will now be at the rotation frequency where the frequency stability of the cryogenic oscillators is the best.P.L. Stanwix, M.E. Tobar, M. Susli, C.R. Locke, E.N. Ivanov, J. Winterflood, J.G. Hartnett, F. van Kann, P. Wol