Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 50 (2017)

Search for low-lying resonances in 10 N structure with proton
resonant scattering
E. Milman,∗1,∗2 T. Teranishi,∗3 S. Sakaguchi,∗1,∗3 K. Abe,∗4 Y. Akiyama,∗1,∗3 D. Beaumel,∗1,∗5
S. Chebotaryov,∗1,∗2 T. Fukuta,∗1,∗3 A. Galindo-Uribarri,∗6 S. Hayakawa,∗4 S. Hwang,∗7 Y. Ichikawa,∗1N. Imai,∗4 D. Kahl,∗4 R. Kaku,∗1,∗3 T. Kaneko,∗1,∗8 D. Kim,∗1,∗9 W. Kim,∗3 N. Kitamura,∗4 Y. Norimatsu,∗1,∗3E. Romero-Romero,∗6 D. Sakae,∗1,∗3 Y. Sakaguchi,∗4 M. Sasano,∗1 K. Tateishi,∗1 T. Uesaka,∗1 K. Yamada,∗1,∗8and H. Yamaguchi∗4
Theoretically, four low-lying 10 N levels are expected
as broad and overlapping resonances1,2) . The levelstructure of 10 N is very important to understand thestructure of its mirror nuclei,10 Li. The information of10Li levels can be used to constrain the 9 Li+n potential, which is required for constructing the three-bodymodel of the borromean nucleus 11 Li.
We proposed the measurement of the excitation
function of the (diﬀerential) cross section and vector
analyzing power (Ay ) for the 9 C+p resonant scattering reaction to determine these broad resonances3) .
In September 2015, a test 9 C+p resonant scatteringexperiment was conducted at RIPS4) , where the production of a low-energy 9 C beam was tested and theexcitation function was measured. The production ofthe 4.17 MeV/nucleon 9 C beam is described in Ref.[5].
The thick-target method in inverse kinematics6) wasused for the measurement, where the excitation function of the cross section is scanned with a single beamenergy utilizing the energy loss of the beam particle in
the target. The range of center-of-mass energy is set to
1−5 MeV to cover the theoretically expected groundstate of 10 N and several excited states.
A 14.85 mg/cm2 polyethylene ﬁlm with a size of
50×50 mm2 was used as the secondary target. An
18.78 mg/cm2 thick carbon ﬁlm was used as well toevaluate the number of background events producedin the interaction of 9 C with carbon in the polyethylene target. The outgoing particles were detected by
two telescopes placed at 22.5◦ and −16◦ . The distances
between the target and telescopes were 18 cm and 24
cm for the 22.5◦ telescope (Tel.1) and −16◦ telescope(Tel.2) respectively. Each telescope consisted of threelayers of silicon semiconductor detectors (SSDs). The
respective thicknesses of SSDs were 46 μm, 1.5 mm,and 1.5 mm for Tel.1 and 57 μm, 1.5 mm, and 1.5 mm
for Tel.2. The sensitive area of each SSD was 48 × 48mm2 which covered ±6.2◦ and ±4.8◦ in the laboratory
frame for Tel.1 and Tel.2, respectively. Double-sided

strip silicon detectors were used as the ﬁrst layer of
the SSDs in the telescopes to determine the scattering
angle of the particles. The particles were identiﬁed by
the ΔE – E method. The protons with energy below
2.2 MeV were identiﬁed by the TOF – E method using
the timing information of the event.
Center-of-mass energy spectra were deduced fromthe measured proton energy and the scattering angle
on an event-by-event basis by assuming the kinematics of elastic scattering and by considering the energy
losses of both the incident heavy ion and the outgoing proton in the target. The energy resolution in thecenter-of-mass frame was estimated to be 150 keV insigma.
The main background sources in the experimentwere reactions of beam particles with carbon in thetarget and beta-delayed protons from the decay of 9 C
ions stopped in the target. The latter contribution
was evaluated by selecting events with a shifted timing, since the coincidence rate for a beam particle and abeta-delayed proton has an accidental character. The
excitation spectrum (Fig. 1) of the 9 C+p resonant
scattering was obtained by subtracting the carbon contribution and the ”beta-delayed” background from thespectrum measured on the polyethylene target.
Resonance parameters will be extracted by an Rmatrix analysis of the spectra.
Counts

31.2×10600

1500
400

0.80.6300
200

0.4

100

0.20

1 1.5 2 2.5 3 3.5 4 4.5 5
Ec.m. [MeV]

0

1 1.5

2

2.5

3

3.5

4 4.5 5
Ec.m. [MeV]Fig. 1. Preliminary excitation spectra of the 9 C+p resonant scattering measured by Tel.1 (left) and Tel.2(right).

References∗1∗2∗3∗4∗5∗6∗7∗8∗91) S. Aoyama, K. Kato, K. Ikeda, Phys. Lett. B 414, 13(1997).
2) E. Caurier et al., Phys. Rev. C 66, 024314 (2002).
3) T. Teranishi et al., AIP Conf. Proc. 1525, 552 (2013).
4) T. Kubo et al., Nucl. Instr. Meth. B 70, 309 (1992).
5) E. Milman et al., RIKEN Accel. Prog. Rep. 49, 160(2015).
6) K.P. Artemov et al., Sov. J. Nucl. Phys. 52, 408 (1990).

RIKEN Nishina Center
Department of Physics, Kyungpook National University
Department of Physics, Kyushu University
CNS, The University of Tokyo
IPN Orsay
Oak Ridge National Laboratory
JAEA
Department of Physics, Toho University
Department of Physics, Ewha Womans University- 73 -