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, Evgeniy Koschiy, Ingo Wiedenhoever, Grigory Rogachev
Florida State University
Dan Bardayan
OakRidge National Laboratory
CSSP 2012
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
(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
18Ne
Reaction of Interest:
14O(α,p)17F
17F
14O
+α
21Na
+p
+α
1
+p
CSSP 2012
Gamow Window
• Due to Coulomb Barrier and MaxwellBoltzmann 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
v 
8

kT  Se

3/2
EG / E E /kT 
e
dE
0
F+p Gamow window
There have been a
number of previous
measurements of
properties of
the 3 most
important states are still
uncertain
Resonant Reaction Rate:
 2

v  
kT 



3/ 2
 2  re  Er / kT
0.0
CSSP 2012
0.2
0.4
Ecm (MeV)
0.6
0.8
ANASEN
•
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
Annular array for
forward/backward angles
CSSP 2012
Active target/detector
Annular gas proportional counter
surrounds beam axis
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
Active Gas Target/Detector
• 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
CSSP 2012
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.
Electronic Output
Solid Target or Gas Target
Proportional Counter
Silicon Detector Inner Array
CsI Outer Array
Heavy Ion
Recoil
Chamber
Nearly 800
signals of
electronics
CSSP 2012
VME Crate of
Electronics
• 72 Channel
Preamp Boxes
(LSU)
• HINP16C ASICs
(Wash. U.)
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
@ 80 MeV
8cm thick
Hydrogen gas at
cooled to 71K by
liquid helium
• 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.
r
Havar 2mg/cm2
16O
Havar 2mg/cm2
In-Flight Technique
17F
16O
@ 55 MeV
@ 46.2 MeV
mv p
2mE


qB qB
qE
17
F @ 55MeV 

16
O @? 

17 * 55
9
16 E
8
17 * 55
16 E
(17 * 55 * 82 )


 E 
 46.2MeV
9
8
(16 * 9 2 )
General
CSSP 2012
2011
Experimental Setup
First measurements with ASIC DAQ
system and heavy ion recoil detector
Double-sided
silicon telescope:
θlab= 9.6° to 28.3°
Test with 17O Beam
Measurement with 17F
from RESOLUT
Thick CH2
target
RESOLUT Beam Line at FSU
CSSP 2012
Isobutane heavy
ion recoil chamber:
θlab= 1.4° to 8.9°
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
First Anode Energy (keV)
DE vs E for Heavy Ion Recoil
Total Heavy Ion Recoil Chamber Energy (keV)
~80% efficiency, this fulfills expectations.
CSSP 2012
Thick Target Technique
17F
• 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
@ 55MeV
17F
@ 35MeV
2mg/cm2
of CH2
152°
• Simultaneously
measure the
17F(p,α)14O and
17F(p,p)17F reactions
• The heavy ion recoil
chamber tags the
reaction
Proton Center of Mass Energy
162°
157°
CSSP 2012
θcm
132°
142°
147°
Lab Angle (radians)
137°
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
Yield
137°
Preliminary R-Matrix Fitting
θcm
Proton Center of Mass Energy (MeV)
Yield
137°
147°
157°
• This should lead to new insight
into the structure of 18Ne via
the 17F(p,p)17F reaction.
CSSP 2012
Proton Center of Mass Energy (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
• Maybe we see p,α from
one of the important
resonances
• But, statistics are
somewhat limited and
we are working to
understand possible
backgrounds
Si Energy (MeV)
Alphas in Coincidence with 14O
General
CSSP 2012
2011
Heavy Ion Energy (MeV)
Future Work
• 17O(d,p)18O Test completed
• 19O(d,p)20O experiment completed
• First RIB experiment with Super X3
and ASICs
Super-X3
E (MeV)
9.0
“backward”
S2
Position in PC
• Full ANASEN working
• He-Gas Target
• Directly measure
14O(α,p)17F
12C(a,a)12C*(2+)
E in Super X3
Lab angle
CSSP 2012
Active target testing for
ANASEN with Stable
beam via 12C(α,α)12C*
Thanks
Also: J. Elson, L. Sobotka, E. Koschiy
General
CSSP 2012
2011