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Measurement of 17 F+p reactions with ANASEN

Measurement of 17 F+p reactions with ANASEN. Astrophysical Background Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) Measurement at FSU 17 O Stable Test 18 Ne via 17 F( p,p ) 17 F and 17 F(p, α ) 14 O Future Work.

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Measurement of 17 F+p reactions with ANASEN

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  1. Measurement of 17F+p reactions with ANASEN Astrophysical Background Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) Measurement at FSU 17O Stable Test 18Ne via 17F(p,p)17F and 17F(p,α)14O Future Work Laura Linhardt, Milan Matos, Charlie Rasco, Hannah Gardiner, Kevin Macon, Jeffrey Blackmon Louisiana State University Daniel Santiago-Gonzalez, Lagy Baby, EvgeniyKoschiy, Ingo Wiedenhoever, GrigoryRogachev Florida State University Dan Bardayan OakRidge National Laboratory CSSP 2012

  2. Nuclear Astrophysics Background • Most common stellar explosions • Novae • X-Ray Bursts • Binary Star system where hydrogen is accreted through the Roche Lobe and builds up on the surface of the companion star. • Nuclear Reactions are crucial, where there are many reactions that have large uncertainties • Understanding these reactions will lead to better stellar models giant star white dwarf (nova) or neutron star (x-ray burst) hydrogen CSSP 2012

  3. (p,) and (α,p) Reactions • Most important nuclear reactions in x-ray bursts are (p,) and (α,p) • Reactions occur at low energies governed by resonant properties near the particle threshold • Information on proton-rich nuclei reactions are needed. • (α,p) Reactions: • Slow rates • Affect X-ray burst light curve • Statistical models still not very reliable at low energies 21Na + p Reaction of Interest: 14O(α,p)17F 18Ne + α 1 17F + p CSSP 2012 14O + α

  4. Gamow Window Studies F+p Gamow window 0.4 0.2 0.6 0.0 0.8 Ecm (MeV) • Due to Coulomb Barrier and Maxwell-Boltzmann Distribution the energies of interest are only hundreds of keV • 17F(p,α)14O is the inverse reaction of 14O(α,p)17F important in x-ray burst. • Negative Q value • Requires a higher beam energy • There have been a number of previous measurements of properties of the 3 most important states are still uncertain Resonant Reaction Rate: CSSP 2012

  5. ANASEN Array Overview • ANASEN is a charged-particle detector array designed for direct measurements of (a,p) reactions and studies of scattering and transfer reactions to improve our understanding of reaction rates for novae and X-ray bursts Up to 1300 cm2 of 1-mm-thick Si backed with 2-cm-thick CsI Up to 3 rings of 12 modules in barrel formation Active target/detector Annular gas proportional counter surrounds beam axis Annular array for forward/backward angles CSSP 2012

  6. Silicon Detector Array (Micron) Super X3 • 3 rings of 12 Super-X3 detectors (32 delivered) • 75mm x 40.3mm  1mm • Front: 4 resistive strips 75mm x 10mm • Back: 4 strips 18.6mm x 40mm non-resistive • Energy from back • Position: Ratio of largest front signal to back QQQ3 CSSP 2012

  7. Active Gas Target/Detector • Cylindrical proportional counter surrounding beam axis • 19 anode wires 43 cm long • 7mmdiamcarbon fiber  High Gain • High, uniform resistivity (4kW/cm) • Good position resolution • 8 grounded cathode electrodes surround anode in trapezoidal shape  19 identical cells • Inner and Outer cylinders of shielding electrodes • Positive bias prevents external elecrons (e.g. delta electrons due to beam ions) from entering active area • Large dynamic range: • High energy protons DE~10 keV • Scattered heavy ions DE~10 MeV MESYTEC logarithmic, multi-channel preamps CSSP 2012

  8. ANASEN in Total First Phase of Testing ANASEN • Heavy Ion Recoil Chamber • HINP16C Application Specific Integrated Circuit (ASIC’s) electronic system • 17F(p,p)17F elastic and inelastic scattering and 17F(p,α)14O reaction to understand the combine structure of 18Ne. • VME Crate of Electronics • 72 Channel Preamp Boxes (LSU) • HINP16C ASICs (Wash. U.) Solid Target or Gas Target Proportional Counter Silicon Detector Inner Array CsI Outer Array Heavy Ion Recoil Chamber Electronic Output Nearly 800 signals of electronics CSSP 2012

  9. Exotic Nuclei at FSU’s RESOLUT • Cesium sputter ion source or a laser-pumped polarized lithium ion source • Super-FN tandem • Carbon foil strippers • Turbo-pumped recirculating gas stripper • Superconducting linear accelerator • 12 accelerating resonators in 3 cryostats • In-flight radioactive beam facility (RESOLUT) • Nuclear reactions are produced in a cryogenic gas cell and products are collected by a superconducting resonator CSSP 2012

  10. In-Flight Technique 17F @ 55 MeV 16O @ 80 MeV 16O @ 46.2 MeV • Create 16O beam at 80 MeV (5 MeV/u) through tandum and linac. • In flight technic to change the beam into 17F at 55 MeV (3.24 MeV/u) • Calculated with kinematics (LISE+) so that the transition happens in the middle of the gas target • Then went through a rebuncher • Next a separator magnet. 8cm thick Hydrogen gas at cooled to 71K by liquid helium Havar 2mg/cm2 Havar 2mg/cm2 CSSP 2012 General 2011

  11. Experimental Setup First measurements with ASIC DAQ system and heavy ion recoil detector Double-sided silicon telescope: θlab= 9.6° to 28.3° Isobutaneheavy ion recoil chamber: θlab= 1.4° to 8.9° Test with 17O Beam Measurement with 17F from RESOLUT Thick CH2 target RESOLUT Beam Line at FSU CSSP 2012

  12. 17O(p,α)14N – Stable Beam Test Run • 17O(p,α)14N Test Run: • Testing the performance, efficiency, and energy resolution of the experimental system. • Measured 17O+p at 4 different beam energies (Ecm=1.8-3.0 MeV) with thin target Energy vs. Angle correcting for offset DE vs E for Heavy Ion Recoil 17O 14N 17O(p,α)14N 17O(p,p)17O First Anode Energy (keV) 17O(p,p’)17O* Total Heavy Ion Recoil Chamber Energy (keV) ~80% efficiency, this fulfills expectations. CSSP 2012

  13. Thick Target Technique • A thick target allows for us to simultaneously measure all the energies of interest • Measuring the angle and the energy of the light particle determines the center of mass energy θcm 152° 132° 162° 142° 147° 137° 157° 17F @ 55MeV • Simultaneously measure the 17F(p,α)14O and 17F(p,p)17F reactions • The heavy ion recoil chamber tags the reaction 17F @ 35MeV 2mg/cm2 of CH2 Proton Center of Mass Energy CSSP 2012 Lab Angle (radians)

  14. 17F+p Progress Report • R-Matrix code “multi” was used to fit the data • The three different angles show a progressive increase in yield over the range of proton energy Preliminary R-Matrix Fitting θcm 137° 137° 147° Yield Yield 157° • This should lead to new insight into the structure of 18Ne via the 17F(p,p)17F reaction. Proton Center of Mass Energy (MeV) CSSP 2012 Proton Center of Mass Energy (MeV)

  15. 17F(p,α)14O Status • Good particle id for Ea>12 MeV • Lots of fusion evaporation • Integrated beam on target low – expect counts from the strongest resonances 3 MeV Si Energy (MeV) Alphas in Coincidence with 14O 2 MeV • Maybe we see p,α from one of the important resonances • But, statistics are somewhat limited and we are working to understand possible backgrounds Heavy Ion Energy (MeV) Alphas Protons CSSP 2012 General 2011

  16. Future Work • Full ANASEN working • He-Gas Target • Directly measure 14O(α,p)17F • 17O(d,p)18O Test completed • 19O(d,p)20O experiment completed • First RIB experiment with Super X3 and ASICs 3.6 5.4 7.1 2.0(2+) gs(0+) Super-X3 9.0 E (MeV) “backward” S2 Position in PC Active target testing for ANASEN with Stable beam via 12C(α,α)12C* Lab angle 12C(a,a)12C*(2+) CSSP 2012 E in Super X3

  17. Thanks Also: J. Elson, L. Sobotka, E. Koschiy CSSP 2012 General 2011

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