Coulomb dissociation of O-16 into He-4 and C-12

We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Evolution of CALIFA: From single detector modules to benchmark reactions

As one of the key detectors of the R3B setup (Reactions with Radioactive Relativistic Beams) at FAIR (Facility for Antiproton and Ion Research), the CALIFA (CALorimeter for the In Flight detection of γ rays and light charged pArticles) detector array surrounds the reaction target and measures γ rays with energies of 100keV < E_γ < 30MeV as well as light charged particles up to E particle = 700MeV. The entire array will consist of 1952 CsI(Tl) scintillating crystals in the Barrel and 460 crystals in the Endcap part. Each crystal is read-out by a Large Area Avalanche Photo Diode. To match the requirements, several steps, tests and quality assurance procedures have to be fulfilled in order to provide the basic components of the CALIFA array. This work gives a detailed description of the assembly of 120 Endcap detector-units and the equipment of two Endcap segments. Furthermore, a gain-matching procedure is performed on the two Endcap segments and their energy resolution is compared to additional test results on the same crystals and to test data stemming from Barrel detectors. A benchmark experiment was performed at the Bronowice Cyclotron Center in Kraków using the quasi-free scattering reaction 208Pb(p,2p)207 Tl in direct kinematics. Within the scope of the experiment, a monoenergetic proton beam of E beam = 200 MeV impinged on a 208 Pb target and the outgoing protons and γ rays were detected by 3 CALIFA petals, containing 64 crystals each. Additionally, two DSSSDs (Double Sided Silicon Strip Detectors) were used to enable vertex reconstruction. The entire setup was read-out by the CALIFA DAQ and operated in air. As proof of concept, two known γ transitions in 207Tl could be identified studying the reaction 208Pb(p,2p)207Tl. In coincidence with one proton, the transition from the 11/2− state, with a lifetime of 1.33s, could be observed. Furthermore, it could be shown in this work that the coincident measurement of the two outgoing protons together with the γ ray, stemming from the transition of the 5/2+ state to the 3/2+ state in 207Tl, is feasible. For use at FAIR, the performance of the CsI(Tl) detectors matches the requirements of CALIFA. The conducted experiment is the first successful measurement of a (p,2pγ) reaction for such heavy nuclei and therefore was a good test case for experiments planned at FAIR that will investigate nuclei in the third r-process peak

S2-Complete analysis, data, and Rproject

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The multi-dimensional nature of information drives prioritization of private over social information in ants

When personally gathered and socially acquired information conflict, animals often prioritize private information. We propose that this is because private information often contains details that social information lacks. We test this idea in an ant model. Ants using a food source learn its location and quality rapidly (private information), whereas pheromone trails (social information) provide good directional information, but lack reliable information about food quality. If this lack is indeed responsible for the choice of memory over pheromone trails, adding information that better food is available should cause foragers to switch their priority to social information. We show it does: while ants follow memory rather than pheromones when they conflict, adding unambiguous information about a better potential food source (a 2 mu l droplet of good food) reverses this pattern, from 60% of ants following their memory to 75% following the pheromone trail. Using fluorescence microscopy, we demonstrate that food (and thus information) flows from fed workers to outgoing foragers, explaining the frequent contacts of ants on trails. Ants trained to poor food that contact nest-mates fed with good food are more likely to follow a trail than ants which received information about poor food. We conclude that social information may often be ignored because it lacks certain crucial dimensions, suggesting that information content is crucial for understanding how and when animals prioritize social and private information

Data from: The multi-dimensional nature of information drives prioritisation of private over social information in ants

When personally gathered and socially acquired information conflict, animals often prioritise private information. We propose that this is because private information often contains details that social information lacks. We test this idea in an ant model. Ants using a food source learn its location and quality rapidly (private information), whereas pheromone trails (social information) provide good directional information, but lack reliable information about food quality. If this lack is indeed responsible for the choice of memory over pheromone trails, adding information that better food is available should cause foragers to switch their priority to social information. We show it does: while ants follow memory rather than pheromones when they conflict, adding unambiguous information about a better potential food source (a 2µl droplet of good food) reverses this pattern, from 60% of ants following their memory to 75% following the pheromone trail. Using fluorescence microscopy, we demonstrate that food (and thus information) flows from fed workers to outgoing foragers, explaining the frequent contacts of ants on trails. Ants trained to poor food that contact nestmates fed with good food are more likely to follow a trail than ants which received information about poor food. We conclude that social information may often be ignored because it lacks certain crucial dimensions, suggesting that information content is crucial for understanding how and when animals prioritise social and private information

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Oxygen targets and 6-month outcome after out of hospital cardiac arrest: a pre-planned sub-analysis of the targeted hypothermia versus targeted normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial

International audienceAbstract Background Optimal oxygen targets in patients resuscitated after cardiac arrest are uncertain. The primary aim of this study was to describe the values of partial pressure of oxygen values (PaO 2 ) and the episodes of hypoxemia and hyperoxemia occurring within the first 72 h of mechanical ventilation in out of hospital cardiac arrest (OHCA) patients. The secondary aim was to evaluate the association of PaO 2 with patients’ outcome. Methods Preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after OHCA (TTM2) trial. Arterial blood gases values were collected from randomization every 4 h for the first 32 h, and then, every 8 h until day 3. Hypoxemia was defined as PaO 2  300 mmHg. Mortality and poor neurological outcome (defined according to modified Rankin scale) were collected at 6 months. Results 1418 patients were included in the analysis. The mean age was 64 ± 14 years, and 292 patients (20.6%) were female. 24.9% of patients had at least one episode of hypoxemia, and 7.6% of patients had at least one episode of severe hyperoxemia. Both hypoxemia and hyperoxemia were independently associated with 6-month mortality, but not with poor neurological outcome. The best cutoff point associated with 6-month mortality for hypoxemia was 69 mmHg (Risk Ratio, RR = 1.009, 95% CI 0.93–1.09), and for hyperoxemia was 195 mmHg (RR = 1.006, 95% CI 0.95–1.06). The time exposure, i.e., the area under the curve (PaO 2 -AUC), for hyperoxemia was significantly associated with mortality ( p = 0.003). Conclusions In OHCA patients, both hypoxemia and hyperoxemia are associated with 6-months mortality, with an effect mediated by the timing exposure to high values of oxygen. Precise titration of oxygen levels should be considered in this group of patients. Trial registration : clinicaltrials.gov NCT02908308 , Registered September 20, 2016