Darek Seweryniak (Argonne National Laboratory, Chicago, USA)

Wednesday 5th October 2016

From Quarks to Neutron Stars

With masses up to twice the mass of our Sun and radii of about 10km, neutron stars are

among the densest objects in the Universe. Still, they can have a very diverse composition.

The neutron star surface is a solid, while its interior is a liquid mostly made of neutrons.

Deep interior of the neutron stars is still unknown and could be made of quarks, the

smallest elementary particles known to exist. After introducing the standard model of

elementary particles and the theory of strong interaction between quarks, I am going to

discuss the current understandings on the structure of neutron stars in terms of quarks

and other elementary particles. I will also discuss how the observations of neutron stars

can provide information on their internal structure.

medical imaging
Positron Emission Tomography (PET) is increasingly used as a quantitative tool to evaluate the

state of patient disease and assist in the planning for a course of therapy. The ability to use PET

as a truly quantitative technique requires the ability to compare imaging data between different 

scanners, across multiple imaging sites, and even between different radionuclides, all as a function

of time. Such a situation is only possible when all the instrumentation is calibrated to common

standards. National Metrology Institutes, such as the National Institute of Standards and Technology

(NIST) and the National Physical Laboratory (NPL) are responsible for developing the metrology

infrastructure to enable such a scenario.
The methods used to develop the types of radionuclide standards needed for quantitative imaging

are varied, but they all rely, to various degrees, on the quality of the nuclear and atomic data used

as input. This presentation will explore the recent development of standards for several PET

radionuclides at the National Institute of Standards and Technology (NIST), their application in

improving the state of quantitative imaging, and how the nuclear data influence the development

and use of those standards. Finally, specific needs in the area of nuclear data for these types of

radionuclides will be discussed. I will discuss possible improvements based on ab initio techniques.

Friday 16th September 2016

nuclear reactions. Isobaric charge-exchange reactions induced by relativistic nuclei far off

stability are particularly interesting, since they can be used to study the excitation of these

resonances in an isospin-rich nuclear environment and, in addition, can provide valuable

information on the radial distribution of neutrons and protons in nuclei. In this talk, I will present

a model for the study of the Delta and N* resonances in isobaric charge-exchange reactions

of heavy nuclei. Quasi-elastic and inelastic elementary processes contributing to the double

differential cross sections are described in terms of the exchange of virtual pions. The inelastic

channel includes processes where the resonances are excited both in the target and in the

projectile nucleus. I will present results for reactions of 112Sn and 124Sn on different targets.

The results show that the position of the Delta peak is insensitive to targets with mass A>12,

and that the origin of the Delta peak shifts towards low excitation energies, with respect to

the position in reactions with a proton target. Both aspects can be easily explained in terms

of the different excitation mechanisms contributing to the reaction.
 

that the excitation energies of these modes must lie well above the pairing gap in even-even

nuclei. This casts doubt on the textbook identification of the lowest lying excited 02+ and 2+

rotational bands in deformed nuclei as beta and gamma vibrations of the nuclear shape. We

show the properties of the K pi= 02+ levels, at excitation energies below 1.0 MeV in N = 88 and

90 nuclei, indicate that they are two neutron 2p-2h states lowered into the pairing gap by

configuration dependent pairing [1]. The K pi= 2+ bands are truly collective and arise from

the gamma degree of freedom that breaks the axial symmetry. Representations of these

K pi= 2+ excitations as phonons or bosons are deeply flawed.
Modern experimental data indicate that there are no time-dependent vibrations of the nuclear

shape that lie at energies below 2.0 MeV. Collective structures at these energies are due

Thursday 11th August 2016

Towards ab initio nuclear structure, spectroscopy and matrix elements along the nuclear chart
In the last decade there has been an impressive progress in our understanding of atomic nuclei

based on first-principles calculations. Improvements in many-body methods and the use of nuclear

forces based on chiral effective theory allow for so-called ab initio studies not only for the lightest

nuclei but also many medium-mass systems.
I will focus on medium-mass nuclei, comparing the results of theoretical calculations based on

many-body perturbation theory with experimental data, both for ground-state properties and

spectroscopy, including electromagnetic transitions. I would also like to highlight recent

estimations of the theoretical uncertainties associated to these calculations.
Finally, if time allows I will also briefly show results for the nuclear matrix elements relevant for

the nuclear neutrino-less double-beta decay, and the hypothetical interaction of atomic nuclei

with Dark Matter particles. Present studies are mostly phenomenological, and I will discuss

possible improvements based on ab initio techniques.

Friday 24th June 2016

Shell model calculations for medium-mass nuclei with ab-initio effective interaction

I will present the outline and results of shell-model calculations with newly developed

"ab initio effective interactions”. The interactions are derived from the N3LO nuclear

two-body force including in-medium modifications by the EKK method. The Fujita-

Miyazawa three-body force is included with the usual nuclear-matter averaging. The

calculations have been done for two major shells: sd+pf for the Island of Inversion region

and pf+sdg for Ca-Ni region. Results of various interests will be presented, including

level systematics, magic numbers, deformation, etc.

Tuesday 21st June 2016

Tuesday 14th June 2016
Jorge Casalderrey Solana (University of Oxford)

Jets as Probes of Strongly Interacting Matter in Heavy Ion Collisions
In the aftermath of the ultra-relativistic heavy ion collisions performed at RHIC and the

LHC, a very dense hadronic system is formed. At the early stages of those collisions,

the density is so high that quark and gluons are liberated and QCD matter is deconfined.

In few of those collisions, very high-energy sprays of particles, known as jets, are

produced together with deconfined matter. In their way out of the collision zone, the

properties of those jets are modified, which allows us to use them as tomographic

probes of the produced quark-gluon plasma. In this talk I will describe the interaction

of jets with hot, strongly coupled partonic matter and how those interactions can be

used to understand the dynamics of the quark-gluon plasma.

Tuesday 17th May 2016
Magda Zielińska (CEA Saclay, IRFU/SPhN, Gif-sur-Yvette, France)
Nuclear deformation and shape coexistence at N=60 from Coulomb excitation studies

at REX-ISOLDE
Neutron-rich nuclei in the A~100 mass region have been under extensive investigation in

the last four decades, from both theoretical and experimental points of view, due to

observation of a sudden onset of deformation when going from N=58 to N=60. This

effect was initially observed in mass measurements [1] and later confirmed by laser

spectroscopy studies of ground-state quadrupole moments, as well as by a significant

amount of experimental data on low-lying excited states in neutron-rich Sr and Zr isotopes.
Recently, neutron-rich Sr isotopes were investigated using safe Coulomb excitation of

radioactive beams at the REX-ISOLDE facility [2]. The transition probabilities and

spectroscopic quadrupole moments measured in 96,98Sr (N=58,60) allow to draw

definite conclusions about the coexistence of highly-deformed prolate and spherical

configurations that interchange at N=60. In particular, a very small mixing between

the coexisting states is observed, contrary to other shape coexistence regions where

strong mixing is the rule. New beyond-mean-field calculations using the Gogny D1S

interaction in a five-dimensional collective Hamiltonian formalism well describe the

shape change at N=60, but fail to reproduce its rapidity.
Other Coulomb excitation studies in this mass region will be briefly discussed, as well

as perspectives opened by higher beam energies and intensities provided by HIE-ISOLDE.

[1] M. Epherre et al., Phys. Rev. C19, 1504 (1979)
[2] E. Clément, MZ et al., Phys. Rev. Lett. 116, 022701 (2016)
 

Tuesday 19th April 2016
Alessandro Pastore (University of York)
Recent developments of the N3LO Skyrme functional
Starting from the original article of Skyrme, I will discuss a possible extension of the

standard Skyrme interaction, by considering higher order gradient term. Performing

Hartree-Fock calculations in infinite nuclear matter, it is possible to show a link between

the extended Skyrme interaction and any finite range interaction (namely Gogny and M3Y).
The extra flexibility given by the new terms allow us to improve the reproduction of ab-initio

calculation of the infinite medium, and in particular to solve the long standing problem of

the simultaneous reproduction of the spin-isospin decomposition of the equation of state.
I will finally present the first attempt for calculations in finite nuclei, by illustrating the

basic formalism.

Tuesday 12th April 2016
Omar Benhar (INFN and Department of Physics "Sapienza" University, Roma, Italy)

Neutrino-Nucleus Interactions Around 1 GeV
A quantitative understanding of neutrino-nucleus interactions at beam energies  around 

1 GeV is indispensable for the interpretation of the signals detected by  long-baseline 

neutrino oscillation experiments, which exploit nuclear targets to  reach acceptable 

event rates. I will review the present status of theoretical studies of the nuclear response 

to electroweak interactions, and outline the impact of the modelling of nuclear dynamics 

on the determination of neutrino oscillation parameters.  
 

Nucleosynthesis beyond Fe and related nuclear uncertainties
Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical

processes involving light nuclei. Astrophysical sites and conditions are not well known for some of the
processes involved. On the nuclear physics side, different approaches are required, both in theory and

experiment. The main differences and most important considerations are presented for a selection of
nucleosynthesis processes and reactions. Among the discussed issues are uncertainties in sites and

production conditions, the difference between laboratory and stellar rates, important transitions,

thermal population of excited states, and uncertainty estimates for stellar rates.

Monday 7th March 2016

Beta--delayed neutron spectroscopy with trapped fission products

For  decays  where  β−  decay  populates  excitation  energies  above  the  neutron  separation 

energy,  the  daughter  nucleus  may  de-­excite  by  emitting  a  neutron,  a  process  referred 

to  as  β-­delayed  neutron  emission  (βn).  This  decay  mode  influences  abundances  calculated 

in  r-­process  nucleosynthesis  models,  affects  nuclear  reactor  safety  analysis  calculations, 

and  can  illuminate  aspects  of  nuclear  structure.  However,  existing  data  for  neutron-­rich  nuclei 

are  often  incomplete  or  discrepant.  A  newly  developed  recoil-­ion  detection  technique  allows 

for  high-­precision  βn  branching  ratio  and  neutron  energy  measurements,  without  the  difficulties 

associated  with  direct  neutron  detection.  In  this  approach,  ions  are  trapped  using  a  Beta-­Paul 

trap  surrounded  by  an  array  of  detectors.  Upon  decay,  recoiling  daughter  nuclei  and  emitted 

particles  emerge  from  the  center  of  the  trap  with  minimal  scattering.  The  neutron  energy  can 

be  determined  from  the  time-­of-­flight,  and  hence  momentum,  of  the  recoiling  ions.  In  this 

talk,  I  will  summarize  the  latest  results  from  the  experiment  conducted  at  CARIBU.  
 

This material is based upon work supported by the Department of Energy, National Nuclear 

Security Administration, under Award Numbers DE-­NA0000979 (NSSC), DE-­AC52-­07NA27344 

(LLNL); Office of Nuclear Physics Contract DE-­AC02-­06CH11357 (ANL), and grants DE-­FG02

-­94ER40834 (University of Maryland), DE-­FG02-­98ER41086 (Northwestern University); NSERC, 

Canada, under Application No. 216974; and the Department of Homeland Security. A. Czeszumska

acknowledges support from the Lawrence Scholar Program at LLNL.  

techniques and in scientific computing have opened new avenues for modeling low-energy

light-ion structure and reactions on an equal footing. Starting from chiral effective interactions,

which provide a systematic and improvable scheme based on the underlying theory of QCD,

and equipped with an ab initio method, we are now able to arrive at accurate evaluations of

crucial reaction data for nuclear astrophysics, fusion-energy research, and other applications,

using nuclear effective interactions only con-strained to the A ≤ 3 nucleon systems. I will present

in this talk the No-Core Shell Model with Continuum formalism, which combines square-integrable

A-nucleon eigenstates and continuous binary and ternary cluster states. This method can

accurately describe re-action in systems with more than four nucleons starting from two-and

three-nucleon interactions. I will illustrate the method with the most comprehensive study of the

A=5 and A=6 continuum (N-4He elastic collision [1], 6Li structure and d-4He scattering [3]).

Then, I will consider application to p−shell nuclei using the n-8Be collision as an example [2].

Last, I will discuss our effort to describe the α+n+n three-cluster dynamics [4] and show

preliminary calculations of the d(t,α)n fusion.
 

[1] G. Hupin, J. Langhammer, P. Navratil, S. Quaglioni, A. Calci and R. Roth,

     Phys. Rev. C 88, 054622 (2013); J. Langhammer, P. Navratil, S. Quaglioni, G. Hupin,

     A. Calci and R. Roth, Phys. Rev. C 91, 021301 (2015).
[2] G. Hupin, S. Quaglioni, and P. Navratil, Phys. Rev. C 90, 061601 (2014).
[3] G. Hupin, S. Quaglioni, and P. Navratil, Phys. Rev. Lett. 114, 212502 (2015).
[4] C. Romero-Redondo, S. Quaglioni, P. Navratil and G. Hupin, Phys. Rev. Lett. 113,

      032503 (2014).  

Tuesday 23rd February 2016 in room 40AA03

C. M. Petrache (Centre de Sciences Nucléaires et Sciences de la Matière, CNRS/IN2P3,

Université Paris-Saclay, Bât. 104-108, 91405 Orsay, France)

Transverse wobbling and new chiral modes in lanthanide nuclei

The wobbling motion and the chiral symmetry breaking are unique fingerprints of triaxiality

in nuclei and have been intensively studied in recent years. We were involved in the study of

Ce and Nd nuclei: at high spins we identified bands interpreted as the manifestation of a

stable triaxial nuclear shape, presenting various types of collective motion, like tilted axis and

principal axis rotation, wobbling motion, chiral bands. New types of chiral and wobbling motions

will be discussed. Chiral bands in even-even nuclei, which are not predicted by the existing

3D TAC models, are instead predicted by the Generalized Coherent State Model. The possible

experimental evidence of such bands will be discussed.

The wobbling motion proposed in normal-deformed nuclei at low spins, with transverse or

longitudinal geometry of the collective and single-particle angular momenta, will be discussed.

Recently obtained results, as well as the experimental and theoretical challenges in the study

of the wobbling modes will be presented.

We will also discuss the global features of the investigated nuclei, like the J (2) moments of inertia

and their theoretical interpretation, as well as the conclusions we have drawn, some of them quite

surprising, from the systematic study of the high-spin bands of the Nd nuclei from 128Nd to 141Nd.

most powerful machine for the production of exotic nuclei. At intermediate masses, it is

pushing the frontier of existence towards areas until now inaccessible, and below Fluorine

it is leading us well beyond. We will see how the first SAMURAI campaign has mapped

both sides of the neutron dripline from Beryllium to Oxygen, present some very exotic

preliminary results (like the formation of 21B, 25N or 26O), and discuss the improvements

of the setup that will lead us soon to measure 28O, 7H and the tetra-neutron.