Underground nuclear astrophysics
Transcription
Underground nuclear astrophysics
Underground nuclear astrophysics Helmholtz International Summer School "NUCLEAR THEORY AND ASTROPHYSICAL APPLICATIONS" Dubna, July 21 - August 1, 2014 Tamás Szücs for the LUNA collaboration Dr. Tamás Szücs | Institut for Radiation Physics | t.szuecs@hzdr.de | www.hzdr.de Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 2 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 3 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Origin of the chemical elements C+Si burning r-, s-, pprocesses H+He burning Big Bang 2 3 4 5 20 30 40 50 Charged particle induced reactions Page 4 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Rate Hydrogen burning in stars: pp-chain, normal and hot CNO-cycle Page 5 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 An age of precision for solar neutrinos from the pp-chain BPS 2008 solar model Borexino, SNO+ SNO, SuperK Nuclear data must match the precision of -astronomy: Water-Cherenkov detectors, assuming large neutrino mixing angle: 4% precision 5% precision Page 6 for solar 8B neutrino flux (SNO, SuperK) [B. Aharmim et al., PRC 87, 025501 (2013)] for solar 7Be neutrino flux (Borexino) [G. Bellini et al., PRD 89, 112007 (2014)] Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The proton-proton chain Impact of cross section on neutrino flux Be and B from model: Borexino, SNO+ BeBe BB 3He(3He,2p)4He 2.2% 2.1% 3He(,)7Be 4.6% 4.3% -- 7.7% Reaction SuperK, SNO 7Be(p,)8B Before LUNA it was 7.5% A. Serenelli et al., Phys. Rev. D 87, 043001 (2013) Page 7 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 8 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Nuclear reaction cross section (s) for charged particles • Typical Coulomb barrier height : ~ MeV • Typical temperature kB * T ~ keV The energy dependence of the cross section is dominated by the tunneling probability. Tunneling probability (for relative angular momentum l=0): exp Z1Z 2 E Thermal neutron capture: ~1 barn Page 9 Charged-particle capture at astrophysical energies: s ~ 1 nanobarn!! “NANO - ASTROPHYSICS” Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 How much is the astrophysically relevant energy? The Gamow peak Maxwell-Boltzmann velocity distribution Tunneling probability (for zero relative angular momentum): Page 10 exp Z1Z 2 E Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The Gamow peak, some examples Scenario Reaction EG[keV] s [barn] Detected events/hour Sun (16 MK) 3He(,)7Be 23 10-17 10-9 14N(p,)15O 28 10-19 10-11 AGB stars (80 MK) 14N(p,)15O 81 10-12 10-4 Big bang (300 MK) 3He(,)7Be 160 10-9 10-1 2H(,)6Li 96 10-11 10-3 1 barn= 10-24 cm2; assume 1016 s-1 beam, 1018 at/cm2 target, 10-2 detection efficiency Extrapolations seem to be necessary. Page 11 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Extrapolation and the astrophysical S-factor 3 He, Be 7 1 2 sE e SE E Geometrical cross section s-wave Coulomb Barrier transmission 2 Z1Z 2 E Page 12 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 13 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Typical signal Relative error of the peak area: S S B Page 14 S 1 S S S 2B 1 2B 2 S S S Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Confidence limits Critical limit: L C k 2B Detection limit: L D k 2k 2B 2 Page 15 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 16 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 What contributes to the laboratory background? Energetic muons Radioisotopes in the laboratory: 238U - daughters 232Th - daughters 40K Passive shield Detector Neutrons created in the passive shield or laboratory walls by muons (,n) Red: Radioisotopes in detector and shield: 238U - daughters 232Th - daughters 60Co Neutrons from outside: - cosmic ray - (,n) in rock E < 3 MeV Green: E < 3 MeV and E > 3 MeV Page 17 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Laboratory background at the Earth’s surface Natural radioisotopes Page 18 Cosmic-rays, mainly muons Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Laboratory background at the Earth’s surface using passive shield HPGe spectra recorded at the surface of the Earth: Black, no shield Red, commercial lead shield Typically ~1 count/hour laboratory background in HPGe spectra at E> 3 MeV Lead does not do much at E> 3 MeV. Help!!! Page 19 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Laboratory background at the Earth’s surface using active shielding Factor of 10 – 100 reduction at E> 3 MeV Is it not enough? Page 20 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Why to go underground, an example Scenario Reaction EG[keV] s [barn] Detected events/hour AGB stars (80 MK) 14N(p,)15O 81 10-12 10-4 1 barn= 10-24 cm2; assume 1016 s-1 beam, 1018 at/cm2 target, 10-2 detection efficiency Without background, for 10% precision one need 100 counts. With this count rare it would take 115 years. This is practically impossible. BUT approach as close as possible: Consider 100 times higher rate. (10-2 event/h) Background count rate (event / hour) Without background Time needed to reach 10% precision (years) 0 1.1 Typical overground settings with active shield 2*10-2 3.4 Deep underground 4*10-4 1.2 Page 21 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Attenuation of the laboratory background underground Surface Felsenkeller/DE Gran Sasso/IT The issues are: Energy loss of passing muons in the detector Active shield Page 22 Interaction of cosmic-ray nucleons in the detector 10m rock (,n) neutrons from natural radioactivity in the walls Passive shield Neutrons generated by muons 500m rock Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits /The 3He(,)7Be reaction/ Page 23 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Laboratory background for E > 3 MeV Deep underground the background count rate is 3 order of magnitude lower at E> 3 MeV What about the lower energies? Page 24 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Laboratory background for E < 3 MeV E = 1.5 MeV Earth’s surface: 4 counts/hour Shallow, ~110 mwe: 0.13 counts/hour Gran Sasso, ~3800 mwe: 0.007 counts/hour Page 25 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA 0.05 MV accelerator, 1992-2001 • • 50 kV accelerator deep underground Direct experimental data ruled out a possible nuclear solution for the solar neutrino problem Solar Gamow peak covered with data • 3He(3He,2p)4He cross section Claus Rolfs LUNA 50 kV accelerator Page 26 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA laboratory at Gran Sasso / Italy LUNA-MV, under preparation ~140 km from Rome 1000 m above sea level 1992-2001 Easy access (motorway) 2000-2014+ Italian national laboratory ~100 local staff ~1400 m rock Page 27 106 µ-reduction 103 n-reduction ~600 external users Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The LUNA 0.4 MV accelerator LUNA approach: Measure at or near Gamow peak, using • high beam intensity • low background • great patience Page 28 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The LUNA beam lines Page 29 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground -counting facilities In-beam -spectroscopy underground Rock Closed passive shield Activated sample Detector Open passive shield Rock overburden attenuates cosmics: n, µ, Target (µ,n) Beam Passive shield attenuates Passive shield radionuclides in the laboratory Detector Anti-radon flushing with “old” air/nitrogen Activation at an accelerator e.g. at the surface of the Earth, -counting underground Page 30 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The proton-proton chain Impact of cross section on neutrino flux Be and B from model: Borexino, SNO+ BeBe BB 3He(3He,2p)4He 2.2% 2.1% 3He(,)7Be 4.6% 4.3% -- 7.7% Reaction SuperK, SNO 7Be(p,)8B Before LUNA it was 7.5% A. Serenelli et al., Phys. Rev. D 87, 043001 (2013) Page 31 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be: How does it work? Measuring the promptly emitted -rays, so-called prompt- approach: S(0) = 0.507±0.016 (Adelberger et al., Rev. Mod. Phys. 1998) Measuring the created 7Be activity, so-called activation approach: S(0) = 0.572±0.026 Page 32 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be at LUNA (activation and prompt- technique) Windowless 3He gas target, with 3He recirculation Page 33 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be Page 34 at LUNA, in-beam -spectra Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be at LUNA, 7Be activation spectra Detected 7Be activities: 0.8 - 600 mBq Page 35 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be Page 36 at LUNA, systematic uncertainty -efficiency 1.8% Beam intensity 1.5% Target density 1.5% 7Be 0.7% losses Systematic uncertainty, activation 3.0% Systematic uncertainty, prompt- 3.6% Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 3He(,)7Be at LUNA, S-factor results Sun, 16 MK Big Bang, 300-900 MK Page 37 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Impact of the 3He(,)7Be data: More precise inputs for solar 7Be, 8B neutrinos Impact of cross section s on neutrino flux Be from model: Reaction BeBe 3He(3He,2p)4He 2.2% 3He(,)7Be 4.6% 7.5% was before BUT now 2.5% needed Borexino, SNO+ SuperK, SNO Page 38 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Solar neutrino fluxes: Data and model predictions Neutrino fluxes: Standard Solar Model; Antonelli et al., 1208.1356 GS98 = Old, high CNO elemental abundances AGSS09 = New, low CNO elemental abundances 7Be, 8B: 13N, 15O: Need smaller error bars for the models! Data more precise than the models No data yet, but models are not very precise Slide 39 Daniel Bemmerer | HK 49.1: Underground nuclear astrophysics in Europe | DPG, 20.03.2014 | http://www.hzdr.de Impact of the 3He(,)7Be data: No solution for lithium puzzle of Big Bang nucleosynthesis 7Li, big bang Big bang production 3He(,)7Be* 7Li 2H(,)6Li Observations: Asplund et al. 2006 Big bang abundances: Serpico et al. 2004 6Li, Page 40 big bang Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA 0.05 MV + 0.4 MV science program for astrophysics Machine Reaction Astrophysics 50 kV (1991-2000) 3He(3He,2p)4He pp-chain 2H(p,)3He pp-chain 3He(,)7Be pp-chain, big bang 14N(p,)15O CNO cycle 15N(p,)16O CNO cycle II 25Mg(p,)26Al MgAl cycle 23Na(p,)24Mg NeNa cycle 2H(,)6Li big bang 17O(p,)18F CNO cycle III 17O(p,)18F CNO cycle III 18O(p,)19F CNO cycle IV 18O(p,)19F CNO cycle IV 22Ne(p,)23Na NeNa cycle 400 kV (2001-2014) Page 41 complete running Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA 0.4 MV science program for astrophysics until 2018 Reaction Astrophysics 12C(p,)13N CNO cycle 13C(p,)14N Page 42 2H(p,)3He big bang 6Li(p,)7Be big bang 22Ne(,)26Mg s-process 13C(,n)16O s-process Complemented and extended by the MV machine Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA collaboration Italy Genova F. Cavanna, P. Corvisiero, F. Ferraro, P. Prati Gran Sasso A. Best, A. Formicola, S. Gazzana, M. Junker, L. Leonzi, A. Razeto Milano A. Guglielmetti (LUNA spokeswoman), D. Trezzi Napoli G. Imbriani, A Di Leva Padova C. Broggini, A. Caciolli, R. Depalo, R.Menegazzo Roma C. Gustavino Teramo O. Straniero Torino G. Gervino Hungary Debrecen Z. Elekes, Zs.Fülöp, Gy. Gyürky, E. Somorjai Germany Bochum C. Rolfs, F. Strieder, H.-P. Trautvetter Dresden D. Bemmerer, T. Szücs, M. Takács Edinburgh M. Aliotta, C. Bruno, T. Davinson, D. Scott UK Page 43 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Further reading (incomplete list) • Textbooks: – – • Review articles: – – • C. Rolfs and W. Rodney: Cauldrons in the Cosmos. University of Chicago Press 1988. C. Iliadis: Nuclear Physics of Stars. Wiley-VCH 2007. C. Broggini, D. Bemmerer, A. Guglielmetti, and R. Menegazzo: LUNA: Nuclear Astrophysics Deep Underground. Annual Review of Nuclear and Particle Science 60, 53-73 (2010) H. Costantini, A. Formicola, G. Imbriani, M. Junker, C. Rolfs, and F. Strieder: LUNA: a laboratory for underground nuclear astrophysics. Reports on Progress in Physics 72, 086301 (2009) Paper series about the background: – D. Bemmerer et al. (LUNA collaboration): Feasibility of low-energy radioactive capture experiments at the LUNA underground accelerator facility. European Physical Journal A 24, 313-319 (2005) – A. Caciolli et al. (LUNA collaboration): Ultra-sensitive in-beam -spectroscopy for nuclear astrophysics at LUNA. European Physical Journal A 39, 179-186 (2009) – T. Szücs et al. (LUNA collaboration): An actively vetoed Clover -detector for nuclear astrophysics at LUNA. European Physical Journal A 44, 513-519 (2010) – T. Szücs et al.: Shallow-underground accelerator sites for nuclear astrophysics: Is the background low enough? European Physical Journal A 48, 8 (2012) Page 44 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Underground nuclear astrophysics Nuclear reactions building up the material of our universe Charged particle induced reaction Thermal movement Coulomb barrier Typical energy region Signals in a typical measurement Peak area determination Confidence limits Background Sources Reduction techniques Importance of the underground measurements Typical background underground Push the limits Page 45 Planned upgrade of LUNA and other sites Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 The European perspective 1st Workshop on “Underground nuclear-reaction experiments for astrophysics and applications”, Dresden/Germany April 2010: 30 participants from 8 countries, all projects represented http://www.hzdr.de/felsenkeller ”Due to the extensive science programme, the long running time per experiment, and the number of researchers involved (...), most participants see it necessary to call for at least two European underground facilities to be realized. (...) A consensus emerged that all facilities should be as open as possible to the community (...). The observational and computational astrophysicists should be included at the earliest stage, helping drive and define the science agenda and creating the added value of multidisciplinarity (...)”. NuPECC Long Range Plan 2010, released on 8 December 2010: http://www.nupecc.org “An immediate, pressing issue is to select and construct the next generation of underground accelerator facilities. Europe was a pioneer in this field, but risks a loss of leadership to new initiatives in the USA. Providing an underground multi-MV accelerator facility is a high priority. There are a number of proposals being developed in Europe and it is vital that construction of one or more facilities starts as soon as possible.” “Round Table LUNA-Megavolt at Gran Sasso”, Gran Sasso/Italy 10.-11.02.2011 3rd workshop on “Underground nuclear-reaction experiments for astrophysics and applications” Canfranc/Spain, April 2012 „Starting-up the LUNA MV collaboration”, Gran Sasso/Italy 06.-08.02.2013 Page 46 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Science case for a higher-energy accelerator underground (1) Reactions providing the neutrons for the astrophysical s-process • • 13C(,n)16O Stellar helium burning • 12C(,)16O • 14N(,)18F • 15N(,)19F • 18O(,)22Ne 22Ne(,n)25Mg Carbon burning • 12C(12C,)20Ne Heil et al. 2008 Page 47 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Science case for a higher-energy accelerator underground (2) Solar composition problem • 3He(,)7Be, E>0.4 MeV • 14N(p,)15O, E>0.4 MeV Radionuclides seen in space • 26Al, 44Ti, 60Fe Applied physics • 1H(15N,)12C, hydrogen depth profiling • Proton-induced -emission (PIGE) Page 48 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Gran Sasso / Italy: LUNA-upgrade 3.5 MV accelerator, site identified Idea: 3.5 MV single-ended accelerator, with ECR ion source. LUNA 0.4 MV LUNA 3.5 MV Courtesy A. Guglielmetti Page 49 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Canfranc / Spain 600 m2 (40x15x12) 150 m2 (15x10x7) Depth: 800 m Muons: 0.2 to 0.4 x 10-2 m-2 s-1 Ventilation: 11.000 m3/h Courtesy L. Fraile Page 50 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Facility outside Europe: CASPAR @ Homestake / USA Aggressive time line: Installation complete by mid-2015 • • • • • Relocation of Notre Dame 1 MV accelerator Effective energy range ~ 150 keV – 1 MeV Beam production in range of 100 – 150 µA protons and alphas Current plan for refurbishment and upgrade Recirculating windowless gas target Courtesy D. Robertson, M. Wiescher (Notre Dame) Page 51 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Attenuation of the laboratory background underground Surface Felsenkeller/DE Gran Sasso/IT The issues are: Energy loss of passing muons in the detector Active shield Page 52 Interaction of cosmic-ray nucleons in the detector 10m rock (,n) neutrons from natural radioactivity in the walls Passive shield Neutrons generated by muons 500m rock Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Using an active shielded detector underground Surface Felsenkeller/DE One and the same Clover type HPGe detector with BGO veto Gran Sasso/IT Page 53 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Felsenkeller / Germany, 47 m deep underground laboratory • • • ice cellar of former Felsenkeller brewery, 5 km from Dresden city center -counting facility founded in 1982 Activation studies for nuclear astrophysics 14N(p,)15O, 12C(,)16O Factor of 2.3 difference T. Szücs et al, EPJA 48, 8 (2012) Page 54 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Attenuation of the laboratory background underground Surface Felsenkeller/DE Gran Sasso/IT Freiberg/DE Page 55 The issues are: Energy loss of passing muons in the detector Active shield Interaction of cosmic-ray nucleons in the detector 10m rock (,n) neutrons from natural radioactivity in the walls Passive shield Neutrons generated by muons 1000m rock Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Freiberg mine / Germany 90m 150m Klimakammer 230m Freiberg Page 56 • Silver mine founded in 1168 • Recently a Teaching, Research and Visitor Mine • TU Bergakademie Freiberg Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Freiberg mine / Germany Page 57 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 High energy background comparison with the Clover detector Free running spectra Page 58 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 High energy background comparison with the Clover detector Escape suppressed spectra Page 59 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Why not place a used accelerator in Felsenkeller? Access from outside Tu n nel IX n Tu ne lV III I II lV ne V el nn Tu n Tu d new lab 5MV Plann e N EC el V l IV n Tun ne Tun Tunnel III Tunnel II Tunnel I Ion source i ist Ex ng u co γin g nt la b 20 m Page 60 Industrial area (former Felsenkeller brewery) Additional space available underground Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Felsenkeller, muon flux measurement Rock overburden 130 m.w.e., slightly higher than in the nearby existing lowactivity lab (110 m.w.e.) Courtesy László Oláh Page 61 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Felsenkeller shallow-underground accelerator laboratory for nuclear astrophysics 12 year old 5MV Pelletron system from York/UK MC-SNICS 134 sputter ion source 12 July 2012: Still assembled, in York Proposed location underground 100 µA C- beam 100 µA H- beam No useful He- beam Home made RF ion source to be mounted to the terminal 100 µA H+ beam 100 µA He+ beam 24 July 2012: Loading of components in York 30 July 2012: Unloading of last component in Dresden Page 62 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Carbon-nitrogen-oxygen (Bethe-Weizsäcker) cycle: 14N(p,)15O Bottleneck Postulated in 1938 • Slowest reaction: 14N(p,)15O • Some of the oldest observed stars burn mainly by CNO • ~0.8% contribution in our Sun CNO neutrinos as a probe of the concentration of carbon and nitrogen in the solar core Page 63 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 14N(p,)15O, how does it work? Some possible experimental approaches: (755)% 1. Study capture to each level separately with HPGe detector (~1% efficiency), then extrapolate in the R-matrix framework 2. Study the total cross section with a summing crystal (~70% efficiency) directly at relevant energies 3. Concentrate on the most uncertain component (ground state capture) with precision data and R-matrix fit 4. Complete the data base over a wide energy range 5. Study ground state capture with indirect methods (51)% (51)% (1515)% Page 64 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 14N(p,)15O, experiment with a summing detector 4 BGO summing crystal Page 65 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 14N(p,)15O, total S-factor from three LUNA experimental campaigns Schröder et al. 1987 LUNA 2004-2006-2008 TUNL 2005 total only 15O(GS) Page 66 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 LUNA divided the 14N(p,)15O cross section by 2! Capture to... NACRE compilation 1999 LUNA, phase 1 2004 TUNL 2005 LUNA, phase 3 2008+2011 ...ground state in 15O 1.55 0.34 0.25 0.06 0.49 0.08 0.27 0.05 ...excited states in 15O 1.65 0.05 1.36 0.05 1.27 0.05 (1.39 0.05) 3.2 0.5 (tot) 1.6 0.2 (tot) 1.8 0.2 (tot) 1.66 0.12 (tot) S(0) in keV barn Adelberger et al. 2011 recommended precision 7%... M. Marta et al., Phys. Rev. C 83, 045804 (2011) ...but it should be further improved! Slide 67 Daniel Bemmerer | Underground accelerators | ATHENA final workshop, 15.05.2014 | http://www.hzdr.de Astrophysical implications of the LUNA 14N(p,)15O data 14N(p,)15O cross section cut in half! S(0) = 3.2 keV barn (1998) 1.66±0.12 keV barn (2011) 1. Independent lower limit on the age of the universe, through turnoff luminosity of main sequence stars in the oldest globular clusters: 14±2 billion years. 2. CNO contribution to solar burning reduced by a factor 2, now 0.8% of energy production. 3. More efficient dredge-up of carbon to the surface of asymptotic giant branch stars. 4. A chance to now measure carbon+nitrogen content of solar core with neutrinos. Page 68 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Age determination of very old stars (in globular clusters) Hertzsprung-Russel diagram, turnoff of globular cluster stars from the main sequence Lower CNO rate leads to higher derived age for a given globular cluster How to measure the age of a star cluster: https://www.e-education.psu.edu/astro801/content/l7_p6.html Page 69 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Study of 14N(p,)15O over a wide energy range Solar Gamow peak Important levels in 15O • E = -0.504 MeV, 15O*(6.79) • E = 0.259 MeV • E = 0.987 MeV • E = 2.187 MeV • “background pole” Curves: R-matrix extrapolations Münster 1987 LUNA 2004 TUNL 2005 Page 70 HZDR 2008- Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Experimental setups at the HZDR Tandetron, Dresden Page 71 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 High-energy data on the 14N(p,)15O reaction • • Preliminary data from the Dresden 3 MV Tandetron Also high-energy data influence the R-matrix extrapolation to low energy Page 72 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Doppler shift study of the lifetime of the 6.792 MeV level in E (6792) 0.9 eV = 15O (6792) 0.7fs • • Page 73 Subthreshold level populated in d(14N,n)15O reaction Difficult analysis, expected lifetime ~1 fs Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Nuclear Resonance Fluorescence study of the level widths in 15N 15N) Page 74 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Nuclear Resonance Fluorescence study of the level widths in 15N SE 15N 15N 16O 11B SE SE SESE 11B 16O SE 15N 15N 11B SE SE SE SE SE 15 15N N SE SE 15N 15N SE SE Page 75 15N 15N 15N Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Nuclear Resonance Fluorescence study of the level widths in Page 76 15N Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014 Summary Page 77 Member of the Helmholtz Association Tamás Szücs | t.szuecs@hzdr.de | NTAA Summer School, Dubna, 21.07.-01.08.2014