Measurement of 17 F+p reactions with ANASEN Laura Linhardt, Milan Matos, Charlie Rasco, Hannah...
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Transcript of Measurement of 17 F+p reactions with ANASEN Laura Linhardt, Milan Matos, Charlie Rasco, Hannah...
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