Measurement of 17F+p reactions with ANASEN

Laura Linhardt, Milan Matos, Charlie Rasco, Hannah Gardiner, Kevin Macon, Jeffrey BlackmonLouisiana State University

Daniel Santiago-Gonzalez, Lagy Baby, Evgeniy Koschiy, Ingo Wiedenhoever, Grigory RogachevFlorida State University

Dan Bardayan OakRidge National Laboratory

CSSP 2012

• 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

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

hydrogen

white dwarf (nova) or

neutron star (x-ray burst)

CSSP 2012

(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.

17F + p

18Ne + α

21Na + p

14O + α

Reaction of Interest:14O(α,p)17F

0.0 0.2 0.4 0.6 0.8Ecm (MeV)

F+p Gamow window

CSSP 2012

v 8

kT 3 / 2 Se EG /Ee E / kT

0

dE

• 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

kTErrekTv /2

2/32

Gamow Window Studies

There have been a number of previous measurements of properties of the 3 most important states are still uncertain

Resonant Reaction Rate:

CSSP 2012

Up to 1300 cm2 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 (a,p) reactions and studies of scattering and transfer reactions to improve our understanding of reaction rates for novae and X-ray bursts

ANASEN Array Overview

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

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 DE~10 keV• Scattered heavy ions DE~10 MeV

MESYTEC logarithmic, multi-channel preamps

Active Gas Target/Detector

CSSP 2012

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.

ANASEN in Total

Solid Target or Gas TargetProportional CounterSilicon Detector Inner ArrayCsI Outer Array

Electronic Output

Heavy IonRecoil Chamber

VME Crate of Electronics• 72 Channel

Preamp Boxes (LSU)

• HINP16C ASICs (Wash. U.)Nearly 800

signals of electronics

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

Exotic Nuclei at FSU’s RESOLUT

CSSP 2012

In-Flight Technique

• 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.

General 2011

8cm thick Hydrogen gas at cooled to 71K by

liquid heliumHav

ar 2

mg/

cm2

Havar 2m

g/cm2

16O @ 80 MeV

17F @ 55 MeV

16O @ 46.2 MeV

MeVEE

EO

MeVF

qE

mE

qB

p

qB

mvr

2.46)9*16(

)8*55*17(

8

16

9

55*17

8

16@?

9

55*1755@

2

2

2

16

17

CSSP 2012

Test with 17O BeamMeasurement with 17F from RESOLUT Thick CH2

target

Double-sided silicon telescope: θlab= 9.6° to 28.3°

Isobutane heavy ion recoil chamber: θlab= 1.4° to 8.9°

First measurements with ASIC DAQ system and heavy ion recoil detector

RESOLUT Beam Line at FSU

Experimental Setup

17O(p,α) 14N

17O(p,p)17O

17O(p,p’)17O*

CSSP 2012

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

17O(p,α)14N – 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)

Firs

t Ano

de E

nerg

y (k

eV)

17O14N

CSSP 2012

Thick Target Technique

17F @ 55MeV17F @ 35MeV

2mg/cm2 of CH2

• 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 17F(p,α)14O and 17F(p,p)17F reactions

• The heavy ion recoil chamber tags the reaction

θcm162° 152° 142° 132°

157° 147° 137°Pr

oton

Cen

ter o

f Mas

s En

ergy

Lab Angle (radians)

CSSP 2012

• This should lead to new insight into the structure of 18Ne via the 17F(p,p)17F reaction.

17F+p Progress Report

Yiel

d

Proton Center of Mass Energy (MeV)

137°

147°

157°

θcm

Yiel

d

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

CSSP 2012

Alphas

Protons

General 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 E

nerg

y (M

eV)

3 MeV

2 MeV

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

Alphas in Coincidence with 14O

CSSP 2012

• Full ANASEN working• He-Gas Target • Directly measure

14O(α,p)17F

Future Work

Posi

tion

in P

CE in Super X3

12C(a,a)12C*(2+)

Active target testing for ANASEN with Stable beam via 12C(α,α)12C*

Super-X3

“backward”S2

gs(0 +

)

9.0

7.1

5.43.62.0(2 +)

Lab angle

E (MeV

)

• 17O(d,p)18O Test completed• 19O(d,p)20O experiment completed• First RIB experiment with Super X3

and ASICs

CSSP 2012

Thanks

General 2011Also: J. Elson, L. Sobotka, E. Koschiy