In-beam measurements
13
12
of C+ C fusion reaction cross
section at energies around and
below Coulomb barrier
Ionut-Catalin Stefanescu
Tineri Cercetatori
Decembrie 2016
Outline
Motivation
The 13C+12C Experiment
• In-beam set-up
• Prompt γ measurements using
thick target method
Conclusions
Motivation
• Test the possibilities for direct measurements in nuclear astrophysics
at IFIN-HH  3MV accelerator
• Case study: 13C+12C
• The “real deal” in astrophysics is 12C+12C
• Certify absolute values of the cross sections
• Determine the relative contribution of the channels by measuring prompt
gamma rays
Experimental set-up
12C
target
The 13C+12C experiment in numbers
Prompt γ – 6.4 – 11 MeV
100% HPGe
VC=9.3 MeV (SL)
Ebeam=4.6 - 11 MeV (Ecm=2.2 – 5.28 MeV)
Ibeam = 0.02 – 15 pμA
Shield – 10 cm Pb
48 thick targets in 350 h
13C2+ , 13C3+ ,13C4+
Reactions
12C(13C,α)21Ne
12C(13C,np)23Na
12C(13C,p)24Na
24
23
9.8 MeV
Na+p (472 keV)
Na +np (440 keV)
Ne+α (351 keV)
24Mg+n
12C(13C,2α)17O
12C(13C,n)24Mg
12C(13C,αn)20Ne
17O+2α
(871 keV)
(1369 keV)
In-beam measurements
Steps:
• Energy & efficiency calibration of the HPGe detector
• Irradiation of targets
𝑵𝒑 =
• Data analysis
𝑵𝜸
𝒀𝒙 (𝑬) =
𝜺𝜸 ∙ 𝑵𝒑
𝒀𝟐 − 𝒀𝟏
𝝈 𝑬 =
∙ 𝟏𝟎𝟐𝟒 𝒃
𝑵𝒕
𝑵𝒕 = 𝝆 ∙
𝑵𝑨
𝑨
∙Δx
Reaction channel
Eγ[keV]
εγ
->21Ne+α
->23Na+pn
->24Ne+p
->17O+2α
->24Mg+n
->20Ne+αn
351
440
472
871
1369
1634
0,00187
0,00211
0,00218
0,00257
0,00254
0,00219
𝑸
𝒆∙𝒒
(projectiles)
In-beam measurements
In-beam measurements
neutron
channel
alpha
channel
proton
channel
In-beam measurements
proton channel yield in-beam/activation
proton cross sections
Conclusions
• The experiment was successful, a good combination between 3 MV
TANDETRON and Salt mine!
• No total cross section. Not yet!  Hauser Feshbach theory
simulations to find correction factors for summing and branching ratio
of each reaction channel
• Next steps:
• two more energies down to 4.5MeV&4.4MeV
• 12C+12C (feb 2017) with our colleagues from China
Thank you for your attention! 
Merry Christmas!