Exploring Excited Structure of ?? Through (t,p) Reactions: Results of Experiment IS690

???? First results of experiment IS690: Exploring the excited structure of ? through (t,p) reactions in inverse kinematics Author: Daniel Fern ndez Ruiz Supervisors: Dr. Olof Tengblad, Dra. MJG Borge Experimental Nuclear Physics Group (IEM-CSIC)

Fernndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (1/10) Introduction Daniel Daniel Fe Daeyeong, Korea (1/10) Halo Nuclei The low mass region of the Segre chart is home to multiple types of exotic nuclei. Halo nuclei are one of them. A halo nucleus is a system where the W.F fulfils two main conditions. A large for finding a cluster component fc. A large probability fh of finding one component in a region outside the cluster potentials. Halo First Detection 11Li 11Li The first empirical observation came from scattering experiments of Lithium isotopes, to measure the interaction cross-section of neutron-rich nuclei. 9?? to3 11??, pointing The cross-section drastically increases with the jump from 3 toward a large nuclear radius. [I. Tanihata et al., Phys. Rev. Lett. 55 (1985) 2676.] 9Li This was interpreted as a system, formed by a compact core and an external set of nucleons (3 9??+2n). [P.G. Hansen and B. Jonson, Europhys. Lett. 4 (1987) 409.] 9?? momentum distribution from This hypothesis was confirmed through the 3 11?? break-up experiments. [T. Kobayashi et al., Phys. Rev. Lett. 60 (1988) 2599.] 3

Fernndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (2/10) Why study ???? Daniel Daniel Fe Daeyeong, Korea (2/10) ???? is the archetype of the two neutron halo and thus, can be used to study, among other things. The structure of a three-body bound system since the gs of ???? is well-established as a very complex mixture of waves (p(59(1)%) + s (35(4)%) + d(6(4)%). Di-neutron correlations, since ???? is a Borromean nucleus (a bound three-body system with all subsystems unbound). The excited states of ???? are not well understood, in particular, the existence of a predicted intruder 2s state. The study of these phenomena is linked to a precise understanding of the structure of????.

???? ???? Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (3/10) The still unknown structure of The still unknown structure of Daeyeong, Korea (3/10) Despite the efforts the excited structure of 11Li remains unknown Kubota et al PRL 125, 252501 (2020) Inconclusive results The current knowledge of the structure of 11Li can be summarized as: Diversity in the energy of the excited structure of 11Li. No firm spin assignments. Identification of resonances without incorporating reaction dynamics. Very narrow states are suggested at high energies and continuum at low energies. A new approach to probe the structure would be appreciated

Fernndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (4/10) (t,p) reactions as a probe Daniel Daniel Fe Daeyeong, Korea (4/10) ???? by exciting the very complex g.s. Most experiments try to populate the excited states of ? ??? (g.s) and using the ? populate the excited states of ???? . ???(t,p)? ????* reaction in inverse kinematics to This can be avoided by starting from ? t + 9Li [Xi. Li et al, Phys. A789 (2007)1] d + 10Li [H. An and Ch. Cai, PRC 73, (2006) 054605] p + 11Li: [A.J. Koning & J.P. Delaroche NPA 713, (2003) 231] The 2nd-order DWBA calculation using (FRESCO) gives three reactions channels Calculations by A.Moro (direct Kinematics) ???? can be populated through this reaction The excited states of ? gs or first excited ?+ ???? 2n Pick Up ??? ? ? ? ?? Energy depends on the populated state ???? can be studied via the emitted residual protons. The excited states of ?

Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (5/10) Daeyeong, Korea (5/10) To probe the excited strucutre of ???? through the ???(t,p)????* reaction requires the following: A system to produce a ??? beam and accelerate it to 7 MeV/u ISOLDE+HIE-ISOLDE post-accelerator A reaction chamber to place the detectors, capable of achieving high vacuum and (ideally) previously tested. ISOLDE -Scattering Experimental Chamber (SEC) A particle detection system capable off distinguishing particles with similar mases (p, d, t). The PENTAGON

The PENTAGON Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (6/10) A high cover set up for reaction experiments Daeyeong, Korea (6/10) IV III III II III II I IV II IV PAD 16x16 DSSD E (DSSD) vs E (PAD) p t I: A multi slot target ladder. II: DSSD annular detector, 300 m S5 (120O 145O). III: 5 particle telescopes (60 m DSSD + 1500 m Si-PAD) forming a pentagon (44O 84O). IV: 2 annular DSSDs (60 m S5 + 1000 m S3) forming a particle telescope (6O 32O ). Capable of separating particles

IS690 Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (7/10) A 7 MeV/u beam created irradiating a TaCx, production target with a 1.7 GeV, proton beam (1.27 (21) 106 ions/C a tape station) was guided into SEC, with the PENTAGON set up inside Daeyeong, Korea (7/10) The beam impinged on one of Five targets, that can switched through an external lever 3H/Ti target (Ti foil filled to a 0.4/1 ratio) To measure 9Li (t,p)11Li Titanum Foil To measure the BKG in 9Li (t,p)11Li Deuterated Plastic To measure9Li (t,d)10Li Au target for elastic scattering and beam calibration Empty frame Emitted particles are detected in the PENTAGON and sent through a feed-through to the electronic chain. IS690 took place between 14 to 22 of October 2024 (with a lost day do to a CERN blackout) Data is divided into two broad categories Post blackout (96:48:02) (Low statisitcs) Pre blackout (50:28:05) (High statisitcs) Calibrations where done through elastic sctattering of 12C (05:00:00) and a 4 source (22:11:00)

First results Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (8/10) We aim to identify protons from 9Li (t,p)11Li. Daeyeong, Korea (8/10) DSSD Particles emitted from a reaction can be identified through a characteristic kinematic curve representing the energy of a particle vs the angle of emission. 9Li To distinguish tritium from the BKG channels, 3H and Ti runs are analyzed and compared Second: Isolate the protons Third: compare the proton kinematic curves First: produce a bidimension plot for particle identification Run 96 Titanium (7:45:00) Run 94 Tritium+Titanium (9:22:00) 2411 p/(9:22:00)~4.2 p/min 990 p/(7:45:00)~ 2.12 p/min Comparison of the Ti and 3H 3H/Ti targets indicate a noticeable increase in proton counts.

Fernndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (8/10) First results Daniel Daniel Fe Daeyeong, Korea (8/10) We aim to identify protons from 9Li (t,p)11Li. DSSD Particles emitted from a reaction can be identified through a characteristic kinematic curve representing the energy of a particle vs the angle of emission. 9Li To distinguish tritium from the BKG channels, 3H and Ti runs are analyzed and compared First: produce a bidimension plot for particle identification Second: Isolate the protons Third: compare the proton kinematic curves Run 94 Tritium+Titanium (9: 22: 00) Difference Run 96 Titanium (7: 45: 00) Comparison of the Ti and 3H targets indicate a noticeable increase in proton counts. So there is still some work to be done

Fernndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (9/10) Summary Daniel Daniel Fe Daeyeong, Korea (9/10) ???? are still poorly known, with multiple experiments and ???? gs) producing inconclusive results. The excited states of the halo nucleus theoretical works (several starting from ? ? ???? starting form the ? ??? nucleus and Extepriment IS690 was performed to probe the resonant states of ? using a two neutron pickup reaction in inverse kinematics. A TaCx, production target was irradiated with a 1.7 GeV, proton beam (highest energy for protons at ISOLDE), giving a production of 1.27 (21) 106 ions/C at the tape station. Alternate runs were conducted with, the 3H/Ti target [to observe (t,p)] and the Ti-target [bkg]. Occasional runs with empty-frame [yield], Au [elastic scattering] and DP [(d,p)] targets were also performed. Preliminar analysis shows good initial results. With a noticeable difference (double) in the number of protons obtained from the 3H compared with the Ti target. An in depth analysis is still ongoing.

Daniel Daniel Fe Fern ndez rn ndez Ruiz INPC 2025 Ruiz INPC 2025- -Daeyeong, Korea (10/10) Daeyeong, Korea (10/10) Thank you for your attention !! Any Questions?