Ion stopping in dense plasma target for high energy density physics
Dieter H. H. Hoffmann
Olga N. Rosmej
Naeem Ahmad Tahir
Boris Y. Sharkov
Alexey A. Golubev
Vladimir E. Fortov
- The basic physics of nonrelativistic and electromagnetic ion stopping in hot and ionized plasma targets is thoroughly updated. Corresponding projectile-target interactions involve enhanced projectile ionization and coupling with target free electrons leading to significantly larger energy losses in hot targets when contrasted to their cold homologues. Standard stoppping formalism is framed around the most economical extrapolation of high velocity stopping in cold matter. Further elaborations pay attention to target electron coupling and nonlinearities due to enhanced projectile charge state, as well. Scaling rules are then used to optimize the enhanced stopping of MeV/amu ions in plasmas with electron linear densities nel ~ 10 18 -10 20 cm -2 . The synchronous firing of dense and strongly ionized plasmas with the time structure of bunched and energetic multicharged ion beam then allow to probe, for the first time, the long searched enhanced plasma stopping and projectile charge at target exit. Laser ablated plasmas (SPQR1) and dense linear plasma columns (SPQR2) show up as targets of choice in providing accurate and on line measurements of plasma parameters. Corresponding stopping results are of a central significance in asserting the validity of intense ion beam scenarios for driving thermonuclear pellets. Other applications of note feature thorium induced fission, novel ion sources and specific material processing through low energy ion beams. Last but not least, the given ion beam-plasma target interaction physics is likely to pave a way to the production and diagnostics of warm dense matter (WDM).
Direct photon emission in heavy ion collisions from microscopic transport theory and fluid dynamics : XLVIII International Winter Meeting on Nuclear Physics, BORMIO2010, January 25 - 29, 2010, Bormio, Italy
- Direct photon emission in heavy-ion collisions is calculated within a relativistic micro+macro
hybrid model and compared to the microscopic transport model UrQMD. In the hybrid approach,
the high-density part of the collision is calculated by an ideal 3+1-dimensional hydrodynamic
calculation, while the early (pre-equilibrium-) and late (rescattering-) phase are calculated with
the transport model. Different scenarios of the transition from the macroscopic description to
the transport model description and their effects are studied. The calculations are compared to
measurements by the WA98-collaboration and predictions for the future CBM-experiment are
Towards the Nf = 2 deconfinement transition temperature with O(a) improved Wilson fermions
Bastian B. Brandt
- A lot of effort in lattice simulations over the last years has been devoted to studies of the QCD
deconfinement transition. Most state-of-the-art simulations use rooted staggered fermions, while
Wilson fermions are affected by large systematic uncertainties, such as coarse lattices or heavy
sea quarks. Here we report on an ongoing study of the transition, using two degenerate flavours
of nonperturbatively O(a) improved Wilson fermions. We start with Nt = 12 and 16 lattices and
pion masses of 600 to 450 MeV, aiming at chiral and continuum limits with light quarks.
Thermal transition temperature from twisted mass QCD
Maria Paola Lombardo
- We present the current status of lattice simulations with Nf = 2 maximally twisted mass Wilson
fermions at finite temperature. In particular, the determination of the thermal transition tempera-
ture is discussed.
The spectrum of static-light baryons in twisted mass lattice QCD
- We compute the static-light baryon spectrum with Nf = 2 flavors of sea quarks using Wilson
twisted mass lattice QCD. As light valence quarks we consider quarks, which have the same mass
as the sea quarks with corresponding pion masses in the range 340MeV<∼ mPS<∼ 525MeV, as well as partially quenched quarks, which have the mass of the physical s quark. We extract masses of states with isospin I = 0,1/2,1, with strangeness S = 0,−1,−2, with angular momentum of the light degrees of freedom j = 0,1 and with parity P = +,−. We present a preliminary
extrapolation in the light u/d and an interpolation in the heavy b quark mass to the physical point
and compare with available experimental results.
Constraints for the QCD phase diagram from imaginary chemical potential
Philippe de Forcrand
- We present unambiguous evidence from lattice simulations of Nf = 3 QCD for two tricritical
points in the (T;m) phase diagram at fixed imaginary m=T = ip=3 mod. 2p=3, one in the light
and one in the heavy quark regime. Together with similar results in the literature for Nf = 2 this
implies the existence of a chiral and of a deconfinement tricritical line at those values of imaginary
chemical potentials. These tricritical lines represent the boundaries of the analytically continued
chiral and deconfinement critical surfaces, respectively, which delimit the parameter space with
first order phase transitions. It is demonstrated that the shape of the deconfinement critical surface
is dictated by tricritical scaling and implies the weakening of the deconfinement transition with
real chemical potential. A qualitatively similar effect holds for the chiral critical surface.
Light hadrons from Nf = 2+1+1 dynamical twisted mass fermions
- We present results of lattice QCD simulations with mass-degenerate up and down and mass-split
strange and charm (Nf = 2+1+1) dynamical quarks using Wilson twisted mass fermions at
maximal twist. The tuning of the strange and charm quark masses is performed at three values
of the lattice spacing a ~ 0:06 fm, a ~ 0:08 fm and a ~ 0:09 fm with lattice sizes ranging from
L ~ 1:9 fm to L ~ 3:9 fm. We perform a preliminary study of SU(2) chiral perturbation theory by
combining our lattice data from these three values of the lattice spacing.
Kaon and D meson masses with Nf = 2+1+1 twisted mass lattice QCD
- We discuss the computation of the kaon and D meson masses in the Nf = 2+1+1 twisted mass
lattice QCD setup, where explicit heavy flavor and parity breaking occurs at finite lattice spacing.
We present three methods suitable in this context and verify their consistency.
Forces between static-light mesons
- The isospin, spin and parity dependent potential of a pair of static-light mesons is computed
using Wilson twisted mass lattice QCD with two flavors of degenerate dynamical quarks. From
the results a simple rule can be deduced stating, which isospin, spin and parity combinations
correspond to attractive and which to repulsive forces.
The QCD phase diagram at low baryon density from lattice simulations
- The QCD phase diagram as a function of temperature, T, and chemical potential for baryon
number, mB, is still unknown today, due to the sign problem, which prohibits direct Monte Carlo
simulations for non-vanishing baryon density. Investigations in models sharing chiral symmetry
with QCD predict a phase diagram, in which the transition corresponds to a smooth crossover at
zero density, but which is strengthened by chemical potential to turn into a first order transition
beyond some second order critical point. This contribution reviews the lattice evidence in favour
and against the existence of a critical point.