SNAQ December 2021

Wednesday 8 Dec 2021, 13:45 → 17:30 Europe/Brussels

online (virtual)

Livius Trache (IFIN-HH), Konrad Schmidt (HZDR)

ChETEC-INFRA SNAQs [snacks] Schools on Nuclear Astrophysics Questions

Question in December 2021: Does Nuclear Astrophysics probe fundamental physics?

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Update: Below, all talks are available as PDF for download.

Update: Congratulation to the 2 winners of our SNAQs Scientific Talk Award in recogrecognition and appreciation for giving a scientic talk at the December 2021 edition of SNAQs:

• Ákos Tóth (ATOMKI, Hungary)
• Nikhil Mozumdar (University of Padova, Italy)

And thanks to all other applicants who submitted an abstract.

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This is the 8th edition of a monthly, virtual school format discussing questions related to nuclear astrophysics.

Previous events:	SNAQ Febrauary 2021 SNAQ March 2021 SNAQ April 2021 SNAQ May 2021	SNAQ June 2021 SNAQ October 2021 SNAQ November 2021
Next event:	SNAQ January 2022

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A new event of SNAQs is organized always on the 2nd Wednesday in each month with a break in summer. SNAQs last about 3.5 hours, including breaks, with lectures and scientific talks around a given question in nuclear astrophysics. Lectures are held by senior researchers and scientific talks preferably by young researchers, as master and PhD students. Further, SNAQs put a special focus on the interaction between participants to allow young scientists networking even if traveling to schools, workshops and conferences is not an option.

SNAQs join the community of schools related to nuclear astrophysics that partner with ChETEC-INFRA:

• Carpathian Summer School of Physics (well established)
• European Summer School on Experimental Nuclear Astrophysics (well established)
• Intercontinental School on Nuclear Astrophysics (new)
• International school on nuclear physics, neutron physics and applications (well established)
• Nuclear Physics in Astrophysics School (new)
• Rußbach School on Nuclear Astrophysics (well established)
• School on observations and spectroscopic tools (new)

The aim of this community is to give all students and young researchers the same, multidisciplinary knowledge about nuclear astrophysics. SNAQs will support this idea and strengthen the community of schools by providing a frequent lecture series to train and educate the next generation of scientist with knowledge across the three types of infrastructures used by nuclear astrophysicists:

• astronuclear laboratories supplying reaction data,
• supercomputer facilities performing stellar structure and nucleosynthesis computations, and
• telescopes and mass spectrometers collecting elemental and isotopic abundance data.

Those infrastructures are networked by ChETEC-INFRA, Chemical Elements as Tracers of the Evolution of the Cosmos - INFRAstructures for Nuclear Astrophysics, a new European starting community of 32 partner institutions.

We are looking forward to meet you at the 8th SNAQ.

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SNAQ December 2021 organizer

SNAQs organizing committee

Livius Trache (Horia Hulubei National Institute for Physics & Nuclear Engineering, Romania)

Rosanna Depalo (Università degli Studi di Milano, Italy) Camilla Juul Hansen (TU Darmstadt, Germany) Marcel Heine (Hubert Curien Pluridisciplinary Institute, France) Ann-Cecilie Larsen (University of Oslo, Norway) Andreas Korn (Uppsala University, Sweden) Arūnas Kučinskas (Vilnius University, Lithuania) Mohamad Moukaddam (University of Strasbourg, France) Sara Palmerini (University of Perugia, Italy) Gianluca Pizzone (Laboratori Nazionali del Sud, Italy) Konrad Schmidt (Helmholtz-Zentrum Dresden-Rossendorf, Germany) Olivier Sorlin (Grand Accélérateur National d'Ions Lourds, France) Livius Trache (Horia Hulubei National Institute for Physics & Nuclear Engineering, Romania) Aurora Tumino (Kore University of Enna, Italy)

Guidelines for participants of SNAQs Please, … … rename yourself in the Zoom sessions to match your registration name and institution – this will serve as your “nametag”. … mute your microphone during talks. … use the public chat only for questions related to the lecture; for discussions, please use the private chat. … write your questions in the chat – due to the high number of participants, a moderator will read a selection of questions but can choose a limited number only. … use breakout rooms to talk and chat to each other in smaller groups. Breakout rooms will be available during coffee breaks and participants can choose rooms freely. … behave professionally and respectfully. … follow ethical standards as professional integrity and honesty. … foster a welcoming and inclusive work environment.

13:45 → 14:00 Zoom room available

14:00 → 14:10 Welcome and Introduction

Speaker: Konrad Schmidt (Helmholtz-Zentrum Dresden-Rossendorf, Germany)

SNAQ_2021_12_1_Konrad_Schmidt.pdf

14:10 → 14:20 Carpathian Summer School of Physics

Introduction of the biannual Carpathian Summer School of Physics

Speaker: Livius Trache (IFIN-HH, Romania)

SNAQ_2021_12_2_Livius_Trache.pdf

14:20 → 15:05 Big-Bang Nucleosynthesis as a Probe of Fundamental Physics in the Early Universe

Big-bang nucleosynthesis (BBN) is a quintessential example of how nuclear astrophysics can and does probe fundamental physics. BBN describes the production of the lightest elements during the first three minutes of cosmic time, and represents our earliest reliable probe of the universe. BBN has stood as a cornerstone of both modern cosmology and particle astrophysics, measuring the cosmic baryon content and probing physics beyond the Standard Model. We will review the status of BBN, emphasizing the transformative influence of cosmic microwave background experiments, particularly Planck, in precisely determining the cosmic baryon density, and the impact of recent nuclear reaction measurements. Standard BBN combines this with the Standard Model of particle physics to make tight predictions for the primordial light element abundances. Deuterium observations match these predictions spectacularly, helium observations are in good agreement, but lithium observations (in metal-poor halo stars) are significantly discrepant – this is the ”lithium problem”. Going beyond the Standard Model, BBN probes new physics at play when the universe was seconds old, deep into the radiation era, for example, placing tight limits on any light particles in equilibrium when the Universe was 1 second old. We conclude with a glimpse of prospects for the future.

Speaker: Brian D. Fields (University of Illinois, USA)

15:05 → 15:15 Moderated questions

Speaker: Andreas Korn (Uppsala University, Sweden)

15:15 → 16:00 Nuclear reactions for Standard Solar Models

Speaker: Aldo Serenelli (Institute of Space Science, Spain)

SNAQ_2021_12_4_Aldo_Serenelli.pdf

16:00 → 16:10 Moderated questions

Speaker: Konrad Schmidt (Helmholtz-Zentrum Dresden-Rossendorf, Germany)

16:10 → 16:30 Coffee break and breakout session

Breakout rooms are available to (1) very briefly introduce yourself, (2) talk about the lectures, (3) clarify lecture items, and (4) phrase questions for the round table discussion.

Afterwards, questions can be written in the chat of the main Zoom room. Please tag questions related to lecture 1 with L1 and questions related to lecture 2 with L2. Moderators can only choose a limited number of questions to be discussed at the round table discussion.

This session also povides the opportunity to establish contacts that can be continued using the private chat. Networking is an important tool not only in science.

16:30 → 16:45 Cross section measurement of the 3He(α,γ)7Be reaction with γ-spectroscopy

The astrophysically important 3He(α,γ)7Be reaction plays role both in models of the Big Bang Nucleosynthesis (BBN) through the production of 7Li and in the p-p chain of solar hydrogen burning. In the case of the former event the Gamow energy of the reaction is around 0.2 MeV, while in the case of the p-p chain in the Sun, an order of magnitude less, around 0.023 MeV. Experimental investigation at such low energies is very difficult, if possible all, thus low energy extrapolation inevitable to predict the reaction rate at these energies. There are many precision datasets between Ec.m. = 0.3 – 3.1 MeV, but only two outside of this region, one below and one above. At higher energies known levels of 7Be exist, but those were investigated only in scattering experiments. No experimental radiative capture cross section data are available, which motivates the study of the reaction in that energy range. Therefore, we are performed irradiations, using the ATOMKI MGC-20 cyclotron type accelerator in the energy range of Ec.m. = 4.3 – 8.3 MeV. For the cross-section determination, the activation technique was used. A thin windowed gas cell filled up with 3He gas was used for the experiments, as a target. The reaction product 7Be has a half-life of 53.22 days. The number of collected radioactive 7Be reaction products was determined by gamma spectroscopy. A high purity germanium (HPGe) detector was utilised to measure the 477.6 keV gamma rays following 10.44% of the decays. The preliminary results will be presented.

Speaker: Ákos Tóth (ATOMKI, Hungary)

SNAQ_2021_12_5_Ákos_Tóth.pdf

16:45 → 16:50 Moderated questions

Speaker: Livius Trache (IFIN-HH, Romania)

16:50 → 17:05 Underground measurement of the D(p,γ)3He reaction: nuclear and cosmological implications

The Big Bang Nucleosynthesis (BBN) encompasses the sequence of nuclear reactions in the early minutes of the Universe leading to the production of light nuclei. Among the light elements produced during BBN, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density. Amidst all the reactions involving deuterium production or destruction, the deuterium burning reaction D(p,γ)3He has the largest uncertainty in its cross section which limits the theoretical predictions based on BBN. A recent work by the LUNA collaboration1, reports the cross sections for the D(p,γ)3He reaction in the energy range of 30 <Ecm < 260 keV with minimised uncertainties (<3%). This is based on an experiment carried out deep underground in order to exploit the reduced cosmic ray background at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Gran Sasso Laboratory (Italy). The experiment involved bombarding a high purity extended deuterium gas target with an intense proton beam from the LUNA 400-kV accelerator. The γ rays produced in the ensuing nuclear reaction were detected with the help of a High Purity germanium detector. These experimental results settles the most uncertain nuclear physics input to BBN calculations and substantially improves the reliability of using primordial abundances as probes of the physics of the early Universe. A systematic study of the angular distribution of this D(p,γ)3He reaction has also been performed on the same experimental data. The full energy peak, broadened due to the kinematics has been fit using Legendre polynomials Pℓ, considering ℓ = 0-3. Two separate methodologies have been adopted for the peak shape analysis. Finally, the coefficients obtained from the analysis are reported and compared to those predicted by theoretical ab-initio calculations. A very good agreement with the theoretical predictions is observed.

Speaker: Nikhil Mozumdar (University of Padova, Italy)

SNAQ_2021_12_6_Nikhil_Mozumdar.pdf

17:05 → 17:10 Moderated questions

Speaker: Livius Trache (IFIN-HH, Romania)

17:10 → 17:30 Round table discussion

Questions that were compiled in the chat during and after lectures and breakout session will be answered and discussed.

Speaker: Livius Trache (IFIN-HH, Romania)