1. Measurement of 17 F+p reactions with ANASEN Laura Linhardt, Milan Matos, Charlie Rasco, Hannah Gardiner, Kevin Macon, Jeffrey Blackmon Louisiana State University Daniel Santiago-Gonzalez, Lagy Baby, Evgeniy Koschiy, Ingo Wiedenhoever, Grigory Rogachev Florida State University Dan Bardayan OakRidge National Laboratory CSSP 2012 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

2. 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 hydrogen white dwarf (nova) or neutron star (x-ray burst) CSSP 2012

3. (p,  ) and (α,p) Reactions (α,p) Reactions: Slow rates Affect X-ray burst light curve Statistical models still not very reliable at low energies CSSP 2012 1 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. 17 F + p 18 Ne + α 21 Na + p 14 O + α Reaction of Interest: 14 O(α,p) 17 F

4. 0.0 0.2 0.4 0.6 0.8 E cm (MeV) F+p Gamow window CSSP 2012 Due to Coulomb Barrier and Maxwell- Boltzmann Distribution the energies of interest are only hundreds of keV 17 F(p,α) 14 O is the inverse reaction of 14 O(α,p) 17 F 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:

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

6. CSSP 2012 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 Silicon Detector Array (Micron) Super X3 QQQ3

7. CSSP 2012 Cylindrical proportional counter surrounding beam axis 19 anode wires 43 cm long 7mm diam carbon 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  E~10 keV Scattered heavy ions  E~10 MeV MESYTEC logarithmic, multi-channel preamps Active Gas Target/Detector

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

9. CSSP 2012 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

10. CSSP 2012 In-Flight Technique Create 16 O beam at 80 MeV (5 MeV/u) through tandum and linac. In flight technic to change the beam into 17 F 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. General 2011 8cm thick Hydrogen gas at cooled to 71K by liquid helium Havar 2mg/cm 2 16 O @ 80 MeV 17 F @ 55 MeV 16 O @ 46.2 MeV

11. CSSP 2012 Test with 17 O Beam Measurement with 17 F from RESOLUT Thick CH 2 target Double-sided silicon telescope: θ lab = 9.6° to 28.3° Isobutane heavy ion recoil chamber: θ lab = 1.4° to 8.9° First measurements with ASIC DAQ system and heavy ion recoil detector RESOLUT Beam Line at FSU Experimental Setup

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

13. CSSP 2012 Thick Target Technique 17 F @ 55MeV 17 F @ 35MeV 2mg/cm 2 of CH 2 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 Simultaneously measure the 17 F(p,α) 14 O and 17 F(p,p) 17 F reactions The heavy ion recoil chamber tags the reaction θ cm 162° 152° 142° 132° 157° 147°137° Proton Center of Mass Energy Lab Angle (radians)

14. CSSP 2012 This should lead to new insight into the structure of 18 Ne via the 17 F(p,p) 17 F reaction. 17 F+p Progress Report Yield Proton Center of Mass Energy (MeV) 137° 147° 157° θ cm Yield Proton Center of Mass Energy (MeV) 137° Preliminary R-Matrix Fitting 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

15. Alphas Protons CSSP 2012General 2011 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) Si Energy (MeV) 3 MeV 2 MeV 17 F(p,α) 14 O Status Good particle id for E a >12 MeV Lots of fusion evaporation Integrated beam on target low – expect counts from the strongest resonances Alphas in Coincidence with 14 O

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

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