Stato dell’esperimento LUNA e del progetto LUNA MV- CdS MI giugno 2014 Laboratory Underground Nuclear Astrophysics Alessandra Guglielmetti Università degli Studi di Milano e INFN, Milano, ITALY L’esperimento LUNA: misure recenti e programmi futuri Stato del Progetto Premiale LUNA MV Alessandra Guglielmetti & Davide Trezzi (assegnista UNIMI)

Hydrogen burning 4p  4He + 2e+ + 2e + 26.73 MeV pp chain p + p  d + e+ + ne d + p  3He + g 3He +3He  a + 2p 3He +4He  7Be + g 7Be+e- 7Li + g +ne 7Be + p  8B + g 7Li + p  a + a 8B 2a + e++ ne 84.7 % 13.8 % 13.78 % 0.02 % pp chain

BBN reaction network Be Li He p D H n 1. n  p + e- + n p + n  D + g 3 4 Be 7 Li H D p n 2 1 8 9 6 11 12 10 5 13 1. n  p + e- + n p + n  D + g D + p  3He + g D + D  3He + n D + D  3H + p 3H + D  4He + n 3H + 4H  7Li + g 3He + n  3H + p 3He + D  4He + p 3He + 4He  7Be + g 7Li + p  4He + 4He 7Be + n  7Li + p 4He + D  6Li + g

The two Lithium problems The BBN 7Li predictions are a factor 2-4 higher than observations: a nuclear physics solution is highly improbable (e.g 3He(4He,g)7Be measurement at LUNA) 2) The amount of 6Li predicted by the BBN is about 3 oom lower than the observed one in metal poor stars (debated but still «true» for a few metal poor stars) BBN predicts 6Li/7Li= 2 * 10-5 much below the detected levels of about 6Li/7Li= 5 * 10-2 Necessary to constrain nuclear physics input: 2H(a,g)6Li

Available data No data in the BBN energy range! Upper limits (indirect meas) No data in the BBN energy range!

Experimental setup Strong beam induced background due to: Rutherford scattering of 4He beam on 2H target 2H(d,n)3He reaction Inelastic neutron scattering on different materials (Cu, Pb, Ge,…) g background in the 2H(a,g)6Li RoI The beam induced background weakly depends on the beam energy

Natural background subtracted Gamma spectra An irradiation at one given beam energy can be used as a background monitor for an irradiation at a different beam energy, if the two ROIs do not overlap Natural background subtracted 400 keV data (grey filled) 280 keV data (red empty) rescaled to take into account the weak energy dependence of the beam induced background

M. Anders et al., in press on PRL Results New LUNA data M. Anders et al., in press on PRL From the new data on the 2H(a,g)6Li reaction: 6Li/7Li = (1.5 ± 0.3) * 10-5 Standard BBN production as a possible explanation for the reported 6Li detections is ruled out. “Non standard” physics solutions?

On going measurements (1) 22Ne(p,g)23Na : NeNa cycle of H burning. Active in astrophysical novae Impact on the abundances of 22Ne (factor 100) 23Na (factor 7) 24Mg (factor 70)

Experimental setup and results In red newly discovered resonances Preliminary!

On going measurements (2) 17O(p,a)14N: CNO cycle of Hydrogen burning A. Di Leva et al., PRC 2014 Never measured AGB stars ( T=0.03-0.1 GK ) Rare isotopes production

Experimental setup and results Beam entrance 8 silicon detectors 193 keV resonance of 17O(p,a)14N and 151 keV resonance of 18O(p,a)15N used to: -perform an accurate energy calibration of the Si detectors -measure the thickness of the Al-Mylar foils in front of the detectors with enough accuracy The ROI for the alpha particles emitted in the 70 keV resonance determined solid Ta2O5 target (not visible) 17O enriched

17O(p,a)14N reaction Study of the 70 keV resonance: evidence of a counting excess in the RoI

17O(p,a)14N reaction Preliminary! Off-resonance and Bkg in agreement: No beam induced background On resonance evidence of >5 sigmas Data acquisition concluded. Analysis still ongoing

Publications 2013-2014 -O. Straniero et al., Astrophys. J. 763 (2013), 100 -M. Anders et al., Eur. Phys. J. A 49 (2013), 28 -L. Gialanella, A. Guglielmetti, Scholarpedia 8(5) (2013), 11959 -A. Guglielmetti, Nuclear Physics News 24:1 (2014), 40 -A. Di Leva et al., Phys. Rev. C 89 (2014) 015803 -M. Anders et al., “First direct measurement of the 2H(a,g)6Li cross section at Big Bang energies and the impact on the primordial Lithium problem” in press on Phys. Rev. Lett. -A. Guglielmetti, EPJ web of conference 66 (2014), 07007 -C. Gustavino, EPJ web of conference 66 (2014), 07009 -F. Cavanna, EPJ web of conference 66 (2014), 07004 -A. Formicola et al., Nucl. Instr. and Meth. A 742 (2014), 258 -A. Guglielmetti, Physics of the Dark Universe 4 (2014), 10

LUNA 400 kV present program reaction Q-value (MeV) 17O(p,g)18F 17O(p,a)14N 5.6 1.2 18O(p,g)19F 18O(p,a)15N 8.0 4.0 23Na(p,g)24Mg 11.7 22Ne(p,g)23Na 8.8 D(,)6Li 1.47 Measured & published completed From Oct 2014 June - Sept 2014 From Jan 2015 On the way Measured & published The whole program will be completed by late autumn 2015

LUNA 400 kV new program 2015-2018: a bridge toward LUNA MV Experimental program: 13C(a,n)16O – neutron source (LUNA MV) 12C(p,g)13N and 13C(p,g)14N – relative abundance of 12C-13C in the deepest layers of H-rich envelopes of any star 2H(p,g)3He – 2H production in BBN 22Ne(a,g)26Mg – competes with 22Ne(a,n)25Mg neutron source (LUNA MV) 6Li(p,g)7Be – improves the knowledge of 3He(a,g)7Be key reaction of p-p chain (LUNA MV)

Tentative time schedule 2015 (after October): 2H(p,g)3He (1st beam line 3 months) 2016: 2H(p,g)3He (1st beam line 3 months) + 22Ne(a, g)26Mg (1st beam line 3 months) + 6Li(p,g)7Be (2nd beam line 6 months) 2017: 13C(a,n)16O (1st beam line 9 months) + 12C(p,g)13N (2nd beam line 2 months) 2018: 12C(p,g)13N (2nd beam line 2 months) + 13C(p,g)14N (2nd beam line 10 months)

B node hypothesis : definitely ruled out in September 2013 LUNA-MV Project B node hypothesis : definitely ruled out in September 2013

South side of Hall C: definitely assessed in early 2014 LUNA site LUNA MV (approved) Uterminal = 350 – 3500kV Imax = 500mA (on target) DE = 0.7keV Allowed beams: H+, 4He LUNA 1 (1992-2001) 50 kV LUNA 2 (2000 – …) Uterminal = 50 – 400kV Imax = 500mA (on target) DE = 0.07keV Allowed beams: H+, 4He, (3He) South side of Hall C: definitely assessed in early 2014

LUNA-MV Project

Progetto LUNA-MV Progetto Premiale 2011: 2.8 Meuro Divisione tecnica LNGS sta lavorando sul progettazione tecnica dell’infrastruttura (preparazione sito, schermatura, impianti, …) Valutazione di diverse soluzioni di schermatura relativamente alla riduzione del flusso di neutroni ed alla fattibilità tecnica

40 cm concrete + 40 cm water + 40 cm concrete OPERATIVE TASKS: WHICH WALL? We simulate three possible wall schemes with a total width of 1.20 meters (250 Mevents) 120 cm concrete 40 cm concrete + 40 cm water + 40 cm concrete 20 cm concrete + 80 cm water + 20 cm concrete    

OPERATIVE TASK: HOW TO IMPLEMENT SERVICE ACCESSES? We simulate six possible ventilation schemes, the best is presented here. (500 Mevents)   well below  

Progetto LUNA-MV- tempi 23/04/2014 richiesta l’assegnazione di 3.5 Meuro (premiale 2011 e anticipo su premiale 2012) per acceleratore e impianti collegati su sigla LUNA MV sede LNGS. Ok Direttore LNGS 15/05/2014 presentazione M. Junker al MAC : ok dei referees Rifuggiato e Bisoffi. Verbale trasmesso alla Giunta 13/06/2014 e discusso 24/06/2014. Da avvio gara per acceleratore ad acceleratore LUNA MV funzionante in sala C: 39 mesi Preparazione sito: 12 mesi Ottenimento nulla osta Prefettura: 12-18 mesi Previsione smontaggio OPERA: area libera a dicembre 2016 Da luglio 2014: S. Gazzana ingegnere  nucleare con esperienza nel coordinamento cantieri e sicurezza (GLIMOS) per seguire anche lo smontaggio di OPERA

LUNA-MV Management Structure LUNA-MV Technical Task Forces: Man power LUNA-MV Management Structure PI: Alessandra Guglielmetti (MI) Technical Coordinator: Matthias Junker (LNGS) Physics Coordinator: Paolo Prati (GE) Glimos: Matthias Junker RAE: Matthias Junker LUNA-MV Technical Task Forces: Site Preparation: Junker (LNGS) Technical Infrastructure: Formicola (LNGS) Accelerator: Junker (LNGS) Neutron Shielding: Trezzi (MI) Gas Target: Corvisiero (GE) Solid Target: Imbriani (NA) Data Acquisition, Networking and Data Handling: NN Gamma Detectors: Menegazzo (PD) Neutron Detectors: NN Supporto Divisione Tecnica LNGS Ing. G. Bucciarelli: impianti tecnologici ed impiantistica N. Massimiani: impianti elettrici G. Panella : impianti speciali: comando e controllo Ing P. Martella: impianti edili F. Caracciolo, Ing. R. Adinoldfi: gestione ambientale Ing. D . Franciotti: Resp. Divisione Tecnica LNGS Ing R. Tartaglia, Ing M. Tobia: servizio protezione e prevenzione

THE LUNA COLLABORATION Laboratori Nazionali del Gran Sasso A. Best, A. Boeltzig, A. Formicola, S. Gazzana, M. Junker, L. Leonzi Helmoltz-Zentrum Dresden-Rossendorf, Germany D. Bemmerer, M. Takacs, T. Szucs Università di Padova and INFN, Padova, Italy C. Broggini, A. Caciolli, R. De Palo, R. Menegazzo INFN, Roma 1, Italy C. Gustavino Institute of Nuclear Research (MTA-ATOMKI), Debrecen, Hungary Z. Elekes, Zs. Fülöp, Gy. Gyurky, E. Somorjai Osservatorio Astronomico di Collurania, Teramo, and INFN, Napoli, Italy O. Straniero Ruhr-Universität Bochum, Bochum, Germany F. Strieder Università di Genova and INFN, Genova, Italy F. Cavanna, P. Corvisiero, F. Ferraro, P. Prati Università di Milano and INFN, Milano, Italy A. Guglielmetti, D. Trezzi Università di Napoli ''Federico II'', and INFN, Napoli, Italy A. Di Leva, G. Imbriani, C. Savarese (?) Università di Torino and INFN, Torino, Italy G. Gervino University of Edinburgh M. Aliotta, C. Bruno, T. Davinson, D. Scott

Possibile ingresso di un gruppo INFN Bari Vincenzo Paticchio 40% I Ric INFN Enrica Fiore 40% Ric UNI Roberto Perrino 20-30% Ric INFN membri GrIII con attività nei lab LNL, LNS (ioni pesanti a bassa energia con rivelazione di particelle cariche e neutre) , LNF (fisica ipernucleare a Dafne), Jlab (sonde elettromagnetiche), Triumf e LBNL (rivelatori di neutroni), Cern (ALICE e ATLAS) Antonio Valentini 30% Prof Ass. Luigi Schiavulli 30% Prof Ass. fanno parte di esperimenti in GRV Valentini si interessa di sviluppi di rivelatori e tecniche di deposizione, Schiavulli si occupa di misure di alfa e gamma applicate ai beni culturali che necessitano di basso fondo ambientale.

Possibile collaborazione con NTOF Attività di ricerca su rivelatori di neutroni di interesse sia per LUNA/LUNA MV (misure di sezioni d’urto che prevedono emissione di neutroni) sia per NTOF (misure di interesse astrofisico e applicativo). Sviluppo di nuove tecnologie «3He free» di interesse anche per il campo delle tecnologie nucleari (progetto INFN-E) Attività da svolgere dai due esperimenti di CSN3 e dal gruppo INFN-E dei LNS nell’ambito delle rispettive sigle, senza “scambi” di FTE Due fasi: 1) Caratterizzazione dei flussi di neutroni veloci nelle sale sperimentali LUNA e LUNA MV dei Laboratori Nazionali del Gran Sasso con rivelatori a scintillatore liquido di INFN Bari (vedere slide precedente) già dal 2014/15 2) R&D di un rivelatore a termalizzazione “3He-free” per la misura di neutroni in un vasto range energetico, in reazioni di interesse astrofisico in tempi di 2-3 anni con possibili fondi europei / collaborazione industria

13C(a,n)16O reaction – M. Junker In AGB stars the 13C(a,n)16O reaction generates the neutrons which fuel the s-process producing about half of the stable isotopes beyond iron in the universe. The interesting temperatures are 90 -100 MK, which roughly correspond to Gamow energies between 180 and 200 keV. At present the cross section within the Gamow peak is uncertain by almost one order of magnitude. LUNA-400, using a high efficiency neutron detector, will allow to measure the cross section close to Gamow energies with a precision at the level of 10%. When LUNA-MV will be available these data will be complemented by measurements at higher energies to obtain a data set covering an energy window from 230 keV to 2 MeV. LUNA-400 and LUNA-MV will thus provide a unique data set over a wide energy range, which will allow to establish a robust extrapolation over the full Gamow peak. The result will be a break through for the understanding of the s-process and for nucleosynthesis beyond iron.

13C(a,n)16O reaction – M. Junker Development of Carbon solid state target which can withstand high intensity beam Neutron detector (Notre Dame 3He tubes, Edinburgh has applied for funds to develop a new detector, …) Permission to run alpha beam on Carbon target (expected time 15 months) Total time: 9 months + 6 months preparation Need to dismount present gas target beamline

12C(p,g)13N and 13C(p,g)14N reactions - G. Imbriani The 12C(p,g)13N and 13C(p,g)14N reactions determine the relative abundance of 12C and 13C in the deepest layers of the H-rich envelope of any stars. Both reactions have been studied in the sixties and seventies of last centuries down to about Ep = 100 keV. To better determine the relative abundance it is crucial to reduce the uncertainties below 10% for both processes. The Gamow peak is between 20 and 70 keV and we can approach and/or partially cover it. Target production – collaboration with Organic Chemistry Dep Napoli- Permission to run on C target (see previous slide) HPGe detector with heavy shielding for both reaction: 4 +4 months. Second (solid target) beam line. No additional space BGO detector only for 13C(p,g)14N : 6 months

2H(p,g)3He reaction – C. Gustavino The abundance of light isotopes depends on the competition between the relevant nuclear processes and the expansion rate of the early universe. Therefore, their abundance depends on the Universal baryon density. The study of cosmic microwave background (CMB) radiation provides an accurate measurement of the Universal baryon density in excellent agreement with that obtained from BBN theory (obtained by comparing measured and computed abundance of deuterium). However, the systematic uncertainty of the latter is much higher and dominated by the uncertainties of the 2H(p,g)3He astrophysical S-factor. Other cosmological parameters are affected in the same way

2H(p,g)3He reaction – C. Gustavino Precision study (3%) in the 20 keV< Ecm < 263 KeV energy range, well inside the BBN energy region of interest, with the goal of improving the present 9% systematic uncertainty. As light nuclei are involved in this process, the 2H(p,g)3He reaction is of high interest also in theoretical nuclear physics, in particular for what concern “ab-initio" modelling Windowless gas target HPGe detector (angular distribution) BGO detector Total time: 2 + 4 months

22Ne(a,g)26Mg reaction – D. Bemmerer During the life of any star, the H burning moves from the core (main sequence phase) to a more external shell. So doing, it leaves into the core a certain amount of 14N, as released by the CNO cycle. When the He burning starts, this nitrogen is fully converted into 22Ne through the following chain: 14N(a,g)18F(b+)18O(a,g)22Ne. Then, if the temperature is large enough (T> 300 MK), two competing reactions are activated, namely the 22Ne(a, n)25Mg and the 22Ne(a, g)26Mg . The first is an efficient source of neutrons in the He burning core, as well as in the C burning shell, of massive stars (M> 10 Msun) and in the more massive AGB stars (4 <M/Msun< 6). The second competes with the first and allows the production of a certain amount of 26Mg. In particular, a recent study shows that in massive AGB the nucleosynthesis of all the isotopes between 26Mg and 31P is affected by the uncertainty of the 22Ne(a, g)26Mg reaction rate. The 22Ne(a, n)25Mg reaction will be studied with LUNA MV.

22Ne(a,g)26Mg reaction – D. Bemmerer LUNA windowless gas target filled with recirculating enriched 22Ne gas 4p BGO summing detector Measure the E = 395 keV resonance to address conflicting indirect values of the reaction strength by providing a direct value. Even an upper limit would significantly improve the data base for the neutron source term for the astrophysical s-process. Total time 2-3 months

6Li(p,g)7Be reaction – A. Caciolli The most recent measurement of the cross section discovered a resonance-like structure around 195 keV with a surprising decrease of the S factor in the gamma channel with decreasing energy. Nuclear physics models predict the opposite energy dependence. This behavior could be explained by supposing the existence of a positive parity excited state in 7Be (E = 5800 keV). This proposed state might also shade light onto the origin of the absolute amplitude of the 3He(a, g)7Be cross section. The LUNA measurements on the (p,g) channel could cover in full the energy range of the resonance and of the S factor drop clarifying the properties of this resonance and improving also the R-Matrix calculations both in the gamma and alpha channels.

6Li(p,g)7Be reaction – A. Caciolli 6Li evaporated solid targets HPGe detector for the 6Li(p,g)7Be reaction Si detector for the 6Li(p,a)3He reaction for normalisation and to monitor the target stability Activation measurement using STELLA facility Total time 6 months + 2 months preparation