5th Pre-PAC Workshop for AGATA@LNL

13 May 2024, 09:00 → 14 May 2024, 18:00 Europe/Rome

INFN-LNL

Jose' Javier Valiente Dobon (Istituto Nazionale di Fisica Nucleare), Magda Zielinska (CEA Saclay)

We are pleased to announce the fifth Pre-PAC Workshop for the AGATA physics campaign at LNL. It will take place on May 13^th -14^th, 2024 at the Legnaro National Laboratories and is planned to be held in person.

The forthcoming LNL PAC meeting is planned for July 2024, and will evaluate experiments to be performed in the second half of 2024. During this period, only beams from the TANDEM accelerator will be available at LNL, and AGATA is expected to consist of a minimum of 15 triple clusters (1π solid angle coverage).

The aim of the Pre-PAC Workshop is to assist the spokespersons in putting the strongest cases for their proposals forward through a discussion of the physics to be investigated, and to assess the feasibility of the proposed experiments. This includes all experiments planning to use stable beams from the TANDEM accelerator for studies involving AGATA in a possible combination with PRISMA and/or ancillary detectors that are compatible with PRISMA. Any new projects will have to be presented at this workshop before being submitted to the LNL PAC. In most cases, we will not expect presentations of the projects that have already been discussed at the previous Pre-PAC Workshops. If, however, a new project shows a considerable overlap with a previously discussed project of a different group, both parties will be informed and encouraged to participate in the upcoming Workshop.

Following suggestions from the community, we are planning to include in the workshop a special session dedicated to future experimental projects that will make use of ²³⁸U beams from the PIAVE-ALPI complex, which are currently being developed at LNL. The experiments involving these beams will conclude the physics campaign of AGATA in the PRISMA configuration. The maximum energy of the uranium beam will be 7.2 MeV/u with a maximum current of 1 pnA.

You are welcome to submit Letters of Intent (LoIs) for AGATA in configuration with PRISMA and TANDEM beams, as well for future projects involving uranium beams, via this website, with a deadline of April 29^th, 2024. They are expected to include, in a pdf file, a title, short abstract with a description of the physics case and the experimental setup, information on beam (energy, intensity), target(s), and the justified request of beam time.

The information about the duration of the talks will be given in the Second Circular.

The deadline for registration is May 1^st, 2024.

We warmly recommend the LoI spokespersons to contact as soon as possible the experts of the complementary equipment they intend to use. These contact persons are:

• PRISMA : L. Corradi, F. Galtarossa
• SAURON : M. Balogh, E. Pilotto
• GAL-TRACE : S. Capra
• EUCLIDES: J. Pellumaj, D. Brugnara
• SPIDER: N. Marchini, M. Balogh
• DANTE: K. Rezynkina, B. Gongora Servin
• Gamma-ray scintillators: S. Pigliapoco, A. Giaz
• Plunger: M. Polettini, F. Angelini

5thprePACAGATA@LNL_ScientificProgramme.pdf

AGATA_2Pi_NIMA1049.pdf

AGATA_5thPrePAC_Workshop_LNL_First_circular.pdf

AGATA_Performance_Efficiency_PT.pdf

AGATA_Performance_Resolution.pdf

Fasci_TAP.pdf

PrePAC_technical_info.pdf

Monday, 13 May

14:00 → 15:50 Introduction and status reports

14:00 Welcome from LNL direction

Speaker: Faical Azaiez (Istituto Nazionale di Fisica Nucleare)

14:10 Accelerator Status

Speaker: Enrico Fagotti (Istituto Nazionale di Fisica Nucleare)

14:40 EXOTIC Status and proposed commissioning

Speaker: Sara Pigliapoco (Istituto Nazionale di Fisica Nucleare)

agataPrePAC_13May2024.pdf

15:00 Status of the campaign

Speaker: Jose' Javier Valiente Dobon (Istituto Nazionale di Fisica Nucleare)

Valiente-prePACMay2024.ppt

15:20 Overviews of the LoIs for the 5th Pre-PAC

Speaker: Magda Zielinska (CEA Saclay)

MZielinska_PrePAC5_2024.pdf

15:40 EURO-LABS support

Speaker: Tommaso Marchi (INFN - LNL)

15:50 → 16:20 Coffee break

16:20 → 18:00 LoI 1

16:20 Shape coexistence in $^{82}$Se and its relevance in the $^{82}$Se $\to$ $^{82}$Kr $0\nu\beta\beta$ decay

Through this letter of intent, we propose to investigate the electromagnetic properties of the low-lying states in $^{82}$Se, which is a candidate for the possible $0\nu\beta\beta$ decay to $^{82}$Kr, via a multi-step Coulomb excitation measurement with AGATA and SPIDER. The primary objective is to measure, with suitable accuracy, the diagonal and transition E2 matrix elements connecting the low-lying states. These matrix elements will be used to determine shape parameters on the basis of a rotational-invariant sum-rule analysis, thereby, providing considerable insight into the underlying collectivity and the inherent triaxial nature of the ground-state and gamma bands. These newly determined shape parameters will act as important inputs and constraints for calculations aimed at accurately providing the nuclear matrix elements relevant to the $0\nu\beta\beta$ decay of $^{82}$Se, and shed light on its structure dependence. Four (4) days of beam on target are requested.

Speakers: Nirupama Sensharma, Dr Marco Siciliano (Argonne National Laboratory)

sensharma_82Se.pdf

16:40 Nuclear Shape Coexistence in the $0\nu\beta\beta$ Parent $^{116}$Cd

Neutrinoless double-beta ($0\nu\beta\beta$) decay is a speculated, extremely rare nuclear phenomenon, which can only occur if neutrinos are massive Majorana particles. Theoretical works have shown that the decay rate is extremely influenced by the nuclear shape of the decay partners. In this context, the $^{116}$Cd$\to ^{116}$Sn decay is expected to be a good candidate to observe such an exotic phenomenon. In addition, both decay partners are expected to exhibit nuclear shape coexistence, which may also affect the rate of the $0\nu\beta\beta$ decay.
We propose the multi-step Coulomb-excitation measurement of $^{116}$Cd using the AGATA+SPIDER experimental setup. The aim of the experiment is the determination of the shape of $0_{1,2}^+$ states in terms of the ($\beta_2, \,\gamma$) quadrupole deformation parameters.

Speaker: Dr Marco Siciliano (Argonne National Laboratory)

Siciliano-prePAC2024may_Coulex116Cd.pdf

17:00 Development of Self-calibration technique for AGATA via Coulomb excitation

We propose to develop a new signal basis for AGATA array via Coulomb excitation of $^{28}$Si on a thin $^{197}$Au target using the AGATA + PRISMA setup at LNL. The new signal basis will be obtained in an experimental way using the newly developed self-calibration technique from a long-time $\gamma$-source calibration data. The performance of the new self-calibration basis will be studied from the photo-peak efficiency and energy resolution of the Doppler-corrected $\gamma$-energy spectra from this measurement. The $\gamma$-particle coincidence yields is estimated by the GOSIA code. Sufficient statistics to study the signal basis performance can be achieved in 1 day beam time. This development will benefit general AGATA experiments in future at LNL and other facilities.

Speaker: Michael Anthony Bentley

28SiColex.pdf

17:20 Study of Shape coexistence and Triaxial deformation in Cr isotopes via lifetime measurements

pdf attached

Speaker: Julgen Pellumaj (Istituto Nazionale di Fisica Nucleare)

17:40 Search for the $\gamma$ decay of the narrow near-threshold resonance in $^{11}$B

Abstract
Understanding the structure of near-threshold narrow resonances in C, O and B isotopes is of great importance for nuclear structure studies (e.g., in connection with the onset of collectivization phenomena in cluster nuclei) as well as nuclear astrophysics. In this context, the $\gamma$ decay from near-threshold states, with branches of the order of 10$^{-3}$ – 10$^{-6}$ with respect to particle emission, is one of the most powerful probes of their state wave function. Therefore, highly efficient and high-sensitivity $\gamma$ spectrometers, such as AGATA, are needed. To populate near-threshold resonances in C, O and B isotopes, with cross sections of few mb, fusion reactions induced by intense Li beams on Be, C, Li and B targets can be exploited, followed by the evaporation of a single charged particle, detected in a highly segmented detection system (e.g., a TRACE barrel or GRIT). A remarkable case of study is the decay from a hypothetical narrow resonance in $^{11}$B lying just above the proton-decay threshold, the existence of which has been suggested to explain the observation of unexpectable large proton emission after the β- decay of $^{11}$Be. An explorative experiment performed with GALILEO+TRACE has quoted a $\gamma$-ray branch for this sought resonance, with limited statistical confidence, at 1.12 $\times$ 10$^{-3}$, lying slightly above the theory predictions. AGATA, with a sensitivity gain of more than one order of magnitude, will, therefore, allow more firm conclusions on this peculiar decay branch in $^{11}$B.
This proposal is part of an experimental program on light systems which intends to focus, with similar experimental techniques, on the gamma decay from near-threshold states in additional cases, like neutron-rich $^{17}$O to $^{20}$O.

Speaker: Giacomo Corbari (Università degli Studi di Milano and INFN)

slides_PrePAC_11B.pdf

Tuesday, 14 May

09:30 → 11:10 LoI 2

09:30 Direct measurement of quadruple and octupole deformation of 0vββ candidate daughter 150Sm via Coulomb excitaiton

Neutrinoless double beta (0νββ) decay is a hypothetical radioactive process that proves the Majorana fermion nature of neutrino. Recently, matrix elements were determined in 76Ge (parent) [1] and 76Se (daughter) [2] via Coulomb excitation experiment, enabling a model-independent analysis of the nature of deformation, which is important for calculations for the nuclear matrix elements relevant for 0νββ decay.

A new limit on the half-life of 0νββ decay in 150Nd has been reported by NEMO-3 Collaboration recently [3]. Parent 150Nd and daughter 150Sm are located at the shape transition region at N=88 to N=90 [4]. The 150Nd, 152Sm were proposed to have X(5) dynamical symmetry, which is the critical point between spherical vibrator and axially deformed rotor [5,6]. On the other hand, the proposed vibrational 150Sm has an anomalous sharp increase of kinematic moments of inertia, which exceeds the limit of rigid rotor at high spin. The 150Sm was also proposed to have enhanced octupole collectivity at medium spin [7]. The proper treatment of deformation, including the octupole degree of freedom, for 150Sm is essential for reliably calculating the NMEs for 0νββ decay. However, the precise measurement of deformation and matrix elements for 150Sm is lacking.

In this proposal, we aim to perform a model-independent comprehensive study of the quadrupole-octupole triaxial degree of freedom, based on measured E2 and E3 transition matrix elements in 150Sm via Coulomb excitation. We plan to use 210 MeV 58Ni beam from TANDEM bombarding 150Sm target. Based on preliminary estimates, with a beam intensity of 1.5 pnA, the beam time required is approximately 200 hours. The deexcitation γ rays will be detected by the AGATA tracking array in kinematic coincidence with scattered reaction products recorded with the SPIDER array. Then, the measured γ-ray intensities will be analyzed using the semiclassical, coupled-channel, Coulomb excitation least-squares search code, GOSIA, to determine the matrix elements. We have acquired proficiency in the ‘quadrupole sum-rules', enabling us to derive model-independent values for β2, γ, and β3. The results may directly impact the nuclear matrix elements relevant for neutrinoless double beta decay.

Speaker: Enhong Wang (Shandong University)

pre-PAC-150Sm-Enhong.pdf

09:50 Superallowed 10C β-decay branching ratio measurement with high-count rate: a revised edition of Exp. 22.72.

Please find the attachment.

Speaker: Yonghyun Son

YSon_AGATA_PrePAC_10C.pdf

YSon_AGATA_PrePAC_10C_new.pdf

10:10 Colossal Mirror Energy Differences at A = 36: quest for the 0+3 state in 36S AGATA + SAURON experiment

attached pdf

Speaker: Luca Zago (Istituto Nazionale di Fisica Nucleare)

36S_Tercer0.pdf

10:30 Understanding nuclear isospin by means of the Isobaric Analogue State and the Isobaric Anti Analogue State around A = 60

We propose to perform a (p, n) fusion-evaporation reaction using a 10 MeV proton beam
on a 0.5 mg/cm2 60Ni target. We aim to observe for the first time the 0+ T = 1 Anti Analog
state in 60 Cu. This work will enhance our understanding of the f p-shell region around the
N = Z line and allow us to benchmark it with shell model calculations. The use of the
AGATA and EUCLIDES arrays will provide the identification of the state by removing the
(p, p′) channel. A total of three days of measurement plus one day of preparation will be
necessary to completely identify this state using angular correlations.

Speaker: Pablo Antonio Aguilera Jorquera (Istituto Nazionale di Fisica Nucleare)

10:50 At-rest (near)Yrast spectroscopy in the 78Ni region with the deuteron induced fission of 238U

We propose to populate medium spin states of low-Z fission products from transfer-fission reactions by bombarding a $^{238}U$ thick target with a 26 MeV beam delivered by the LNL Tandem. The objective is to study the energy evolution of N=50 neutron-core breaking states with a view to better quantifying the evolution of the neutron-shell gap, as well as continuing the mapping of intruder states in this region. This will enable us to better understand the origin of the shape coexistence regime that seems to be developing in the close vicinity of $^{78}Ni$.

Speaker: Francois Didierjean

fdj_prePAC_LNL.pdf

11:10 → 11:40 Coffee break

11:40 → 13:20 Perspectives with uranium beams

11:40 Production yields of neutron-rich heavy nuclei in the 238U+124Sn multinucleon transfer reaction

With the present Letter of Intent we propose to measure the production yield of nuclei in the region of
238U via the 238U+124Sn multinucleon transfer reaction, by using the PRISMA+AGATA+DANTE set-up.
Special efforts will be made to get direct information on the mass and charge distributions of heavy transfer products in a region where fission processes are dominant. To this purpose, besides the A, Z, Q-value
distributions of the target-like reaction products detected in PRISMA, we will employ a high resolution kinematic coincidence to extract light-heavy mass-mass correlations and the transfer induced fission probability.
Heavy Z partners will be partly identified via X-ray coincidences. Direct heavy mass identification will be
also attempted via a detailed study of the shape of the mass distributions, following the ongoing analysis
of the very recently performed 208Pb+130Te experiment. By a cross comparison of all this information we
should be able to define at best the A, Z yields of heavy partners. The results will provide valuable inputs
for a variety of studies whose feasibility requires knowledge of the population yields of nuclear species
produced via transfer mechanism and differing by a substantial amount of protons and neutrons from 238U

Speaker: Lorenzo Corradi (Istituto Nazionale di Fisica Nucleare)

LoI_uranio_corradi.pdf

12:00 Synthesis of heavy and superheavy neutron-rich nuclei in multinucleon transfer reactions at grazing angle using Uranium beams

Information on the heaviest elements have been obtained up to now via fusion evaporation reactions. It is however well known that the only nuclei one can reach using fusion-evaporation reactions are neutron deficient and moreover in a very limited number (because of the limited number of beam-target combinations). An alternative to fusion-evaporation could be deep-inelastic collisions. Indeed, theoretical calculations predict large cross-sections for neutron-rich heavy elements production close to zero degrees and at grazing angles. We have recently performed an experiment at Argonne National Laboratory where MNT reactions experiment at zero using a 136Xe beam on a 238U targets. The promising preliminary results.
The goal of this proposal is to investigate deep inelastic reactions mechanisms in the heavy elements’ region using the AGATA germanium array and DANTE detector coupled to PRISMA separator. We thus propose to study the multinucleon transfer reaction using a 238U beam on a 64Ni target angles at 40% above the Coulomb. Such an experiment would pave the way for future synthesis on the synthesis of new superheavy neutron-rich isotopes.

Speaker: barbara sulignano (CEA/Saclay)

12:20 Lifetimes of excited states along and around the N=50 shell closure

PDF attached

Speaker: Andrea Gottardo (Istituto Nazionale di Fisica Nucleare)

gottardo_LoI_fission_lifetimes.pptx

12:40 Pushing the limits of γ-ray spectroscopy of neutron rich fission fragments with AGATA+PRISMA coupling

In the present Letter of Intent, we aim to study the structure of neutron-rich nuclei in the vicinity of $^{78}$Ni. The main focus is to study the states resulting from the coupling of the inert-core excited states and the valence protons in the $N=50$ $^{80}$Zn and $^{79}$Cu nuclei. In addition, the proposed experiment will provide a systematic and pertinent dataset on excited states in this region of the nuclear chart, allowing to push the neutron exoticism up by two neutrons for each atomic number produced, compared to what has been achieved in previous similar studies. The nuclei of interest will be produced in transfer- and fusion-induced fission reactions in inverse kinematics. The PRISMA spectrometer will be used to isotopically identify fission fragments and the AGATA gamma tracking array will be used to measure prompt $\gamma$-rays.

Speakers: Andrea Gottardo (Istituto Nazionale di Fisica Nucleare), Jose' Javier Valiente Dobon (Istituto Nazionale di Fisica Nucleare), Jérémie Dudouet (IP2I)

13:00 Conclusions and general discussion