Nuclear Astrophysics

Nuclear Astrophysics Massive Star-Forming Region in 30 Doradus (Hubble) Image NASA, ESA, Elena Sabbi (ESA, STScI) Acknowledgment Robert O'Connell (UVA), SOC-WFC3<< Frescoes in Cappella degli Scrovegni, Padova Giotto 1303-1305 Federico Ferraro INFN – Laboratori Nazionali del Gran Sasso 29 September – 3 October 2025 Frescoes in Cappella degli Scrovegni, Padova Giotto 1303-1305 Underground Nuclear Astrophysics (with a focus on LUNA) Massive Star-Forming Region in 30 Doradus (Hubble) Image NASA, ESA, Elena Sabbi (ESA, STScI) Acknowledgment Robert O'Connell (UVA), SOC-WFC3<< Frescoes in Cappella degli Scrovegni, Padova Giotto 1303-1305 Federico Ferraro INFN – Laboratori Nazionali del Gran Sasso 29 September – 3 October 2025 Cosmology Stellar evolution Nucleosynthesis Astronomy Solar system Solar neutrinos XXI Workshop on Neutrino Telescopes Nuclear Astrophysics [email protected] 3 Jennifer A. Johnson, Populating the periodic table: Nucleosynthesis of the elements.Science363,474-478(2019).DOI:10.1126/science.aau9540 XXI Workshop on Neutrino Telescopes [email protected] 4 XXI Workshop on Neutrino Telescopes [email protected] Aziz, A.A., Ahmad, N.S., Ahn, S. et al. Progress in nuclear astrophysics of east and southeast Asia. AAPPS Bull. 31, 18 (2021). https://doi.org/10.1007/s43673-021-00018-z 5 The energy of nuclei in a stellar plasma follows a Maxwell-Boltzmann distribution the cross section falls faster than exponentially as the energy decreases The Gamow peak defines the relevant energy range for this reaction to occur Consider a reaction A + B → C + D The reaction rate is given by 𝑟 =𝑁A𝑁Bන 0 ∞𝜙 𝑣 𝜎 𝑣 𝑣d𝑣 Nuclear astrophysics in a nutshell XXI Workshop on Neutrino Telescopes This is valid for reactions involving charged particles [email protected] 6 EXTRAPOLATION The cosmic-ray induced background makes any direct measurement in the Gamow window very challenging (the reaction rate becomes negligible w.r.t. the cosmic-ray induced background) Introducing the astrophysical S-factor S(E) and factorizing the Coulomb interaction term apart: 𝝈 𝑬 =𝟏 𝑬𝒆−𝟐𝝅𝜼 𝑺(𝑬) XXI Workshop on Neutrino Telescopes Nuclear astrophysics in a nutshell [email protected] it is possible to measure the cross section at high energy and extrapolate the astrophysical factor S(E) in the interesting energy range (Gamow window) Indirect measurements can be very helpful too (but they rely on certain assumptions or normalizations) 7 unexpected low-energy resonances may be present in the extrapolation region, enhancing the cross section considerably! XXI Workshop on Neutrino Telescopes The cosmic-ray induced background makes any direct measurement in the Gamow window very challenging (the reaction rate becomes negligible w.r.t. the cosmic-ray induced background) Introducing the astrophysical S-factor S(E) and factorizing the Coulomb interaction term apart: 𝝈 𝑬 =𝟏 𝑬𝒆−𝟐𝝅𝜼𝑺(𝑬) Nuclear astrophysics in a nutshell [email protected] it is possible to measure the cross section at high energy and extrapolate the astrophysical factor S(E) in the interesting energy range (Gamow window) Indirect measurements can be very helpful too (but they rely on certain assumptions or normalizations) 8 unexpected low-energy resonances may be present in the extrapolation region, enhancing the cross section considerably! XXI Workshop on Neutrino Telescopes The cosmic-ray induced background makes any direct measurement in the Gamow window very challenging (the reaction rate becomes negligible w.r.t. the cosmic-ray induced background) Introducing the astrophysical S-factor S(E) and factorizing the Coulomb interaction term apart: 𝝈 𝑬 =𝟏 𝑬𝒆−𝟐𝝅𝜼𝑺(𝑬) Nuclear astrophysics in a nutshell Despite the small cross section, it’s very important to perform direct measurements at low energy! [email protected] it is possible to measure the cross section at high energy and extrapolate the astrophysical factor S(E) in the interesting energy range (Gamow window) Indirect measurements can be very helpful too (but they rely on certain assumptions or normalizations) 9 Background reduction at LNGS gamma background reduction: 104 mostly muons radioactivity XXI Workshop on Neutrino Telescopes Photons in HPGe detectors [email protected] 16 Neutrons in He counters Background reduction at LNGS XXI Workshop on Neutrino Telescopes [email protected] 17 Charged particles in Si detectors Background reduction at LNGS XXI Workshop on Neutrino Telescopes [email protected] 18 Risultati immagini per luna lngs It has been the only deep underground accelerator for nuclear astrophysics for 26 years solar physics (solar neutrinos) cosmological model (Ωb, Neff in Λ-CDM) big bang nucleosynthesis (BBN) stellar nucleosynthesis (H, He and C burning, s-process) XXI Workshop on Neutrino Telescopes [email protected] 19 Nuclear astrophysics at LNGS XXI Workshop on Neutrino Telescopes Bellotti IBF Min. overburden: 3400 mwe muon flux reduction:  106 neutron flux reduction:  103 LUNA 50 kV LUNA 400 kV [email protected] 20 LUNA 50 kV (1991-2001) LUNA 400 kV (2001-today) XXI Workshop on Neutrino Telescopes LUNA-MV @ Bellotti IBF (2023-????) [email protected] 21 Reaction Burning stage Accelerator Range E [keV] Target Detector ³He(³He,2p)⁴He pp -chain LUNA -50kV 16.5 –24.4 Gas Si ²H(³He,p)⁴He pp / e⁻ screening LUNA -50kV 5.4 –31.3 Gas Si ²H(p, γ)³He pp -chain/BBN LUNA -50kV 2.5 –22 Gas 4π –BGO/HPGe BBN LUNA -400kV 70 –260 Gas HPGe ³He( α,γ)⁷Be pp -chain/BBN LUNA -400kV 93 –170 Gas HPGe ²H( α,γ)⁶Li BBN LUNA -400kV 80 –133 Gas HPGe ⁶Li(p, γ)⁷Be BBN LUNA -400kV 60 –350 Solid Si/HPGe ¹² C(p,γ)¹³C CNO LUNA -400kV 60 –370 Solid HPGe/ 4π–BGO ¹³ C(p,γ)¹⁴C CNO LUNA -400kV 60 –370 Solid HPGe/ 4π–BGO ¹³C( α,n)¹⁶O Sprocess LUNA -400kV 230 –300 Solid 3He -counters ¹⁴N(p, γ)¹⁵O CNO LUNA -400kV 70 –228 Gas 4π –BGO LUNA -400kV 119 –370 Solid HPGe ¹⁵N(p, γ)¹⁶O CNO LUNA -400kV 90 –230 Gas 4π –BGO LUNA -400kV 70 –375 Gas HPGe/ 4π–BGO ¹⁷O(p, γ)¹⁸F CNO LUNA -400kV 167 –370 Solid HPGe CNO LUNA -400kV 64.5®, 134 Solid 4π –BGO ¹⁷O(p, α)¹⁴N CNO LUNA -400kV 64.5®, 183® Solid Si ¹⁸O(p, γ)¹⁹F CNO LUNA -400kV 142 –379 Solid HPGe/ 4π–BGO ¹⁸O(p, α)¹⁵N CNO LUNA -400kV 90®,143® Solid Si LUNA -400kV 85 –148 Solid 4π –BGO ²⁰Ne(p, γ)²¹Na NeNa LUNA -400kV 368® Gas HPGe LUNA -400kV 247 –362 Gas HPGe ²²Ne(p, γ)²³Na NeNa LUNA -400kV 156.2®, 189.5®, 259.7® Gas HPGe/4 π–BGO LUNA -400kV 70®, 105®, 215® Gas HPGe/4 π–BGO LUNA -400kV 183 -306 Gas 4π –BGO ²²Ne( α,γ)²⁶Mg NeNa /MgAl LUNA -400kV 334® ²⁴Mg(p, γ)²⁵Al MgAl LUNA -400kV 214® Solid HPGe/4 π–BGO ²⁵Mg(p, γ)²⁶Al MgAl LUNA -400kV 92®, 130®, 189.5®, 304® Solid HPGe/4 π–BGO ²⁶Mg(p, γ)²⁷Al MgAl LUNA -400kV 326® Solid HPGe/4 π–BGO Past measurements XXI Workshop on Neutrino Telescopes [email protected] 22 Electrostatic accelerator Beams: p, 3He, 4He Beam energy: 3-50 keV Beam current: up to 500 µA Energy spread: 20 eV Stability: 0.4 eV/h LUNA 50 kV (1991-2001) XXI Workshop on Neutrino Telescopes [email protected] 23 XXI Workshop on Neutrino Telescopes [email protected] LUNA was established in 1991 to measure the cross section of the reaction ³He(³He,2p)⁴He within the Gamow window (16–27 keV). A possible resonance in this reaction could have explained the low flux of solar neutrinos observed by the Homestake experiment, compared to the predictions of the Standard Solar Model. Such a resonance, in fact, would have reduced the relative contribution of the reaction ³He(α,γ)⁷Be, which is responsible for the production of ⁷Be and ⁸B neutrinos observed at Homestake. 24 3He(3He,2p)4He and the solar 𝜈 problem 3He(3He,2p)4He and the solar 𝜈 problem XXI Workshop on Neutrino Telescopes First direct measurement in the Gamow window At 16.5 keV the cross section is 0.02 pb, corresponding to a reaction rate of approximately 2 events/month. The absence of a resonance in the Gamow window allowed to discard a nuclear solution to the Solar Neutrino Problem LUNA (1996-1999) C. Broggini et al. / Progress in Particle and Nuclear Physics 98 (2018) 55–84 [email protected] 25 Reaction Burning stage Accelerator Range E [keV] Target Detector ¹² C+¹²C Cburning LUNA -MV @ Bellotti IBF 1500 –3500 Solid HPGe/ 4π–NaI ¹⁴N(p, γ)¹⁵O CNO LUNA -400kV 70 –228 Solid 4π –BGO CNO LUNA -MV @ Bellotti IBF 259 –1300 Solid HPGe 19 F(p,γ)20Ne CNO LUNA -400kV Solid 4π –BGO ²²Ne(p, γ)²³Na Sprocess LUNA -MV @ Bellotti IBF 550 –1000 Gas LS/He -Counters ²³ Na(p,α)²⁰Ne NeNa / hot CNO LUNA -400kV 138® Solid Si 24 Mg(p,γ)25Al MgAl LUNA -400kV Solid 4π –BGO/HPGe Present measurements XXI Workshop on Neutrino Telescopes [email protected] 32 The Bellotti Ion Beam Facility Inline Cockcroft Walton accelerator TERMINAL VOLTAGE: 0.2 – 3.5 MV Beam energy reproducibility: 0.01% TV or 50V Beam energy stability: 0.001% TV / h Beam current stability: < 5% / h H+ beam: 500 - 1000 µA He+ beam: 300 - 500 µA C+ beam: 100 - 150 µA C++ beam: 50 pµA XXI Workshop on Neutrino Telescopes [email protected] 33 LUNA mesurements at the Bellotti IBF XXI Workshop on Neutrino Telescopes 14N(p,)15O → completed → 22Ne(,n)25Mg → almost completed → 12C+12C → ongoing → perfect commissioning measurement, useful for calibration purposes SHADES Scintillator-3He Array for Deep-underground Experiments on the S-process CaBS Carbon Burning in Stars [email protected] 34 14N(p,𝛄)15O: the bottleneck of the CNO cycle XXI Workshop on Neutrino Telescopes [email protected] Borexino disfavors “LZ-SSM”, but large uncertainties remain The biggest nuclear contribution to the uncertainty budget comes from the 14N(p,𝛾)15O cross section 35 14N(p,𝛄)15O: the bottleneck of the CNO cycle LUNA recently re-measured the cross section of this reaction (both at the LUNA 400 kV and the Bellotti IBF), investigating •weak transitions to ground state •non-resonant component •angular dependence •summing-in corrections to reduce the TNRR uncertainty to 5% XXI Workshop on Neutrino Telescopes [email protected] 36 XXI Workshop on Neutrino Telescopes 3 High-Purity Germanium detectors allow for •very high energy resolution •close/far geometry •reduced summing-in effect •sensitivity to angular distribution 14N(p,𝛄)15O [email protected] 37 22Ne(α,n)25Mg: neutron source for the s-process ~ half the elements between Fe and Y (56≲A≲90) are produced via the weak s-process in massive stars (M > 8Mʘ) 22Ne(α,n)25Mg is considered the neutron source for the weak s-process convective thermal pulse XXI Workshop on Neutrino Telescopes [email protected] 38 22Ne(α,n)25Mg: need for data! Cross section is highly uncertain: practically no direct data in Gamow window! Capabilities on surface labs exhausted (20 years since last direct measurement) Current lowest rate: 2 reactions/minute One resonance close to Gamow peak upper limits spanning ≈300 keV Many states can contribute to the cross section XXI Workshop on Neutrino Telescopes [email protected] 39 XXI Workshop on Neutrino Telescopes 22Ne(α,n)25Mg Windowless, differentialpumping gas target Enriched 22Ne LS + He-counters [email protected] 40 12C+12C onset as a sliding door in stellar evolution ➢threshold masses for white dwarf vs core-collapse outcomes ➢quiescent C-burning in massive stars ➢ignition of type Ia supernovae ➢ignition of superbursts (triggered by 12C+12C fusion) ➢revival of Hand He-burning (induced by p and α produced because of 12C+12C) Mass Effect of a larger cross section Cooper et al 2009 ApJ 702 660 O Straniero et al. 2016 J. Phys.: Conf. Ser. 665 012008 (E. Bravo et al, Astronomy & Astrophysics, 535(2011)A114) M > Mup ⇒ quiescent C burning (ONe-WD, CC-SN, NS, BH) M < Mup ⇒ no quiescent C burning (CO-WD, Novae, SN-Ia) XXI Workshop on Neutrino Telescopes [email protected] Neutrino luminosity overcomes photon luminosity at the onset of C-burning! 41 12C+12C – first 20 days! 1634 keV 440 keV 12C(12C, p)23Na 440 keV (p1)12C(12C, α)20Ne: 1634 keV (α1) 12C(12C, p)23Na: 1637 keV (p2) 12C(1H, γ)13N 2368 keV 12C(2H, pγ)13C 3090 keV Ecm = 3069 keV Q = 0.878 C ΔT= 142 min XXI Workshop on Neutrino Telescopes [email protected] 48 Lowest energy ever reached in a direct experiment …many more to come… •∼ 1000 Red SuperGiants (RSGs) in the Milky Way, many of them expected to be in the C-burning phase (10 within 1 kpc) •For a nearby 30 M☉ carbon-burning RSG located ∼ 200 pc away: ∼ 105 cm−2s−1 neutrinos reaching Earth, with a spectrum peaking at ∼ 0.6 MeV •Is it possible to detect these neutrinos in underground facilities, particularly in hybrid detectors equipped with water-based liquid scintillator and ultra-fast photodetector (to separate Cherenkov and scintillation light)? •In detectors with a volume comparable to Super-Kamiokande: up to ∼ 50 neutrino events per year with directional information (∼ 103 times smaller rate than CNO neutrinos, ∼ 106 times smaller than estimated background) •although detecting neutrinos from carbon-burning RSGs seems difficult with currently available detector technologies, it could become feasible in the future (exploiting directionality and new detection techniques) XXI Workshop on Neutrino Telescopes [email protected] 49 •∼ 1000 Red SuperGiants (RSGs) in the Milky Way, many of them expected to be in the C-burning phase (10 within 1 kpc) •For a nearby 30 M☉ carbon-burning RSG located ∼ 200 pc away: ∼ 105 cm−2s−1 neutrinos reaching Earth, with a spectrum peaking at ∼ 0.6 MeV •Is it possible to detect these neutrinos in underground facilities, particularly in hybrid detectors equipped with water-based liquid scintillator and ultra-fast photodetector (to separate Cherenkov and scintillation light)? •In detectors with a volume comparable to Super-Kamiokande: up to ∼ 50 neutrino events per year with directional information (∼ 103 times smaller rate than CNO neutrinos, ∼ 106 times smaller than estimated background) •“although detecting neutrinos from carbon-burning RSGs seems difficult with currently available detector technologies, it could become feasible in the future (exploiting directionality and new detection techniques) XXI Workshop on Neutrino Telescopes [email protected] 50 •∼ 1000 Red SuperGiants (RSGs) in the Milky Way, many of them expected to be in the C-burning phase (10 within 1 kpc) •For a nearby 30 M☉ carbon-burning RSG located ∼ 200 pc away: ∼ 105 cm−2s−1 neutrinos reaching Earth, with a spectrum peaking at ∼ 0.6 MeV •Is it possible to detect these neutrinos in underground facilities, particularly in hybrid detectors equipped with water-based liquid scintillator and ultra-fast photodetector (to separate Cherenkov and scintillation light)? •In detectors with a volume comparable to Super-Kamiokande: up to ∼ 50 neutrino events per year with directional information (∼ 103 times smaller rate than CNO neutrinos, ∼ 106 times smaller than estimated background) •although detecting neutrinos from carbon-burning RSGs seems difficult with currently available detector technologies, it could become feasible in the future (exploiting directionality and new detection techniques) XXI Workshop on Neutrino Telescopes [email protected] 51 0-3 years 3-5 years 5-7 years 23Na(p,α)20Ne 19F(p,α)16O6Li(α,)10B 27Al(p,α)24Mg 19F(p,)20Ne 7Li(α,)11B 14N(p,)15O30Si(p,)31P 10B(α,2H)12C 10B(α,p)13C 10B(α,n)13N 11B(α,n)14N 14N(p,)15O18O(α,)22Ne 2H(p,)3He 22Ne(α,n)25Mg 17O(α,)21Ne 2H(α,)6Li 12C+12C (gammas) 15N(α,)19F3He(α,)7Be 13C(α,n)16O14N(α,)18F12C(α,)16O 22Ne(α,)26Mg 12C+12C (particles) 400 kV 3.5MV H burning He burning C burning BBN n sources XXI Workshop on Neutrino Telescopes 52 Plans for the future [email protected] Massive Star-Forming Region in 30 Doradus (Hubble) Image NASA, ESA, Elena Sabbi (ESA, STScI) Acknowledgment Robert O'Connell (UVA), SOC-WFC3<< Frescoes in Cappella degli Scrovegni, Padova Giotto 1303-1305 Conclusions •Nuclear Astrophysics is strongly connected to neutrino physics. This connection worked very well in the past, lets make it work in the future, too. •LUNA has been measuring cross sections of astrophysical interest for over 30 years, and is keeping on with increasing momentum. •New facilities for Underground Nuclear Astrophysics were recently created in Germany, China and the USA and will contribute new results. •New measurements are being performed both at the 400 kV accelerator and at the new Bellotti IBF at LNGS, with possible important consequences on solar neutrinos and solar metallicity. •Thanks to the LUNA Collaboration, in particular PhD students and post-docs, and to all the Services at LNGS, in particular the Accelerators Service. Massive Star-Forming Region in 30 Doradus (Hubble) Image NASA, ESA, Elena Sabbi (ESA, STScI) Acknowledgment Robert O'Connell (UVA), SOC-WFC3<< Frescoes in Cappella degli Scrovegni, Padova Giotto 1303-1305 Thank you for your attention! This statement reflects my personal views and does not represent the position of any institution or the Collaboration. Drawing: FairieDance (REDBUBBLE.com) Palestine XXI Workshop on Neutrino Telescopes [email protected] 55 3He(3He,2p)4He e la risonanza fantasma LUNA 50 kV Setup XXI Workshop on Neutrino Telescopes [email protected] Bersaglio gassoso a pompaggio differenziale Telescopi ΔE –E al silicio Per ridurre il fondo: coincidenze 56 XXI Workshop on Neutrino Telescopes [email protected] 3He(α,γ)7Be(e,ν)7Li*(γ)7Li Prompt Activation Le due tecniche mostravano una discrepanza del 9% 3He(α,γ)7Be - la maggiore fonte di incertezza per 𝛷νpp Visto che il 7Be è instabile, è possibile misurare la sezione d’urto anche contando i nuclei di 7Be che decadono 57