Abstract
High-statistics
$$\pi ^-\pi ^-$$
π
-
π
-
and
$$\pi ^+\pi ^+$$
π
+
π
+
femtoscopy data are presented for Au + Au collisions at
$$\sqrt{s_\mathrm{NN}} = 2.4~\hbox {GeV}$$
s
NN
=
2.4
GeV
, ...measured with HADES at SIS18/GSI. The experimental correlation functions allow the determination of the space-time extent of the corresponding emission sources via a comparison to models. The emission source, parametrized as three-dimensional Gaussian distribution, is studied in dependence on pair transverse momentum, azimuthal emission angle with respect to the reaction plane, collision centrality and beam energy. For all centralities and transverse momenta, a geometrical distribution of ellipsoidal shape is found in the plane perpendicular to the beam direction with the larger extension perpendicular to the reaction plane. For large transverse momenta, the corresponding eccentricity approaches the initial eccentricity. The eccentricity is smallest for most central collisions, where the shape is almost circular. The magnitude of the tilt angle of the emission ellipsoid in the reaction plane decreases with increasing centrality and increasing transverse momentum. All source radii increase with centrality, largely exhibiting a linear rise with the cube root of the number of participants. A substantial charge-sign difference of the source radii is found, appearing most pronounced at low transverse momentum. The extracted source parameters are consistent with the extrapolation of their energy dependence down from higher energies.
The production of Σ0 baryons in the nuclear reaction p (3.5 GeV) + Nb (corresponding to sNN=3.18 GeV) is studied with the detector set-up HADES at GSI, Darmstadt. Σ0s were identified via the decay ...Σ0→Λγ with subsequent decays Λ→pπ− in coincidence with a e+e− pair from either external (γ→e+e−) or internal (Dalitz decay γ⁎→e+e−) gamma conversions. The differential Σ0 cross section integrated over the detector acceptance, i.e. the rapidity interval 0.5<y<1.1, has been extracted as ΔσΣ0=2.3±(0.2)stat±(−0.6+0.6)sys±(0.2)norm mb, yielding the inclusive production cross section in full phase space σΣ0total=5.8±(0.5)stat±(−1.4+1.4)sys±(0.6)norm±(1.7)extrapol mb by averaging over different extrapolation methods. The Λall/Σ0 ratio within the HADES acceptance is equal to 2.3±(0.2)stat±(−0.6+0.6)sys. The obtained rapidity and momentum distributions are compared to transport model calculations. The Σ0 yield agrees with the statistical model of particle production in nuclear reactions.
High-statistics π-π- and π+π+ femtoscopy data are presented for Au + Au collisions at sNN=2.4GeV, measured with HADES at SIS18/GSI. The experimental correlation functions allow the determination of ...the space-time extent of the corresponding emission sources via a comparison to models. The emission source, parametrized as three-dimensional Gaussian distribution, is studied in dependence on pair transverse momentum, azimuthal emission angle with respect to the reaction plane, collision centrality and beam energy. For all centralities and transverse momenta, a geometrical distribution of ellipsoidal shape is found in the plane perpendicular to the beam direction with the larger extension perpendicular to the reaction plane. For large transverse momenta, the corresponding eccentricity approaches the initial eccentricity. The eccentricity is smallest for most central collisions, where the shape is almost circular. The magnitude of the tilt angle of the emission ellipsoid in the reaction plane decreases with increasing centrality and increasing transverse momentum. All source radii increase with centrality, largely exhibiting a linear rise with the cube root of the number of participants. A substantial charge-sign difference of the source radii is found, appearing most pronounced at low transverse momentum. The extracted source parameters are consistent with the extrapolation of their energy dependence down from higher energies.
Flow coefficients v_{n} of the orders n=1-6 are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons, and tritons as a function of centrality, transverse ...momentum, and rapidity in Au+Au collisions at sqrts_{NN}=2.4 GeV. Combining the information from the flow coefficients of all orders allows us to construct for the first time, at collision energies of a few GeV, a multidifferential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation of state of dense baryonic matter.
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Purpose: In a prospective randomized trial we examined whether radiotherapy of painful bone metastases can be shortened using larger single doses without impairing effectivity.
Methods and Materials: ...One hundred patients with painful bone metastases having no prior surgical intervention or treatment with x-ray therapy and has a median follow-up of 12 months analyzed. The primary tumor was located in the breast in 43%, in the lund in 24%, and in the prostate in 14%. The most frequent sites of metastases were the pelvis (31%), the vertebral column (30%), and the ribs (20%). Further percentage of sites were: lower extremity 11%, upper extremity 6%, and skull 2%. Fifty-one patients received a short course radiotherapy with a total dose of 20 Gy in 1 week (daily dose 4 Gy), and 49 patients received 30 Gy in 3 weeks (daily dose 2 Gy).
Results: There were no significant differences in frequency, duration of pain relief, improvement of mobility, recalcification, frequency and pathologic fractures nor survival. There was a light trend favoring 30 Gy in frequency of pain relief and recalcification. Survival was mostly influenced by primary tumor site, Karnofsky performance
Conclusions: Because of the very short life expectancy of patients with metastatic bone disease, we now use 20 Gy in 1 week as our standard to reduce hospital stay.
A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES is used to search for a hypertriton signal. An upper production limit per centrality-triggered event of
on the 3
level is ...derived. Comparing this value with the number of successfully reconstructed
hyperons allows to determine an upper limit on the ratio
, which is confronted with statistical and coalescence-type model calculations.
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