Felsenkeller 5 MV underground accelerator: Towards the Holy Grail of Nuclear Astrophysics 12C(α, γ)16O

D Bemmerer ,Sebastian Hammer,Andreas Wagner,Stefan Reinicke,M Koppitz ,Thomas Hensel ,A R Junghans ,R Schwengner ,B Rimarzig ,S Müller ,Michael Grieger ,T E Cowan ,T Szücs ,S Turkat ,F Ludwig ,Louis K Wagner ,K Stöckel ,M P Takács ,Κ Zuber

doi:10.1051/epjconf/201817801008

D Bemmerer , Sebastian Hammer + Show 17 more

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https://doi.org/10.1051/epjconf/201817801008

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Abstract

Low-background experiments with stable ion beams are an important tool for putting the model of stellar hydrogen, helium, and carbon burning on a solid experimental foundation. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator. The present contribution reviews the status of the project for a higher-energy underground accelerator in Felsenkeller, Germany. Results from γ-ray, neutron, and muon background measurements in the Felsenkeller underground site in Dresden, Germany, show that the background conditions are satisfactory. Two tunnels of the Felsenkeller site have recently been refurbished for the installation of a 5MV high-current Pelletron accelerator. Civil construction work has completed in March 2018. The accelerator will provide intense, 50 μA, beams of 1H+, 4He+, and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.

Highlights

Experimental nuclear astrophysics aims to understand the origin of the chemical elements by laboratory experiments [1].One challenging case is the 12C(α, γ)16O reaction
The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator
There are no direct cross section data in the astrophysically relevant energy range, so the present knowledge of its rate depends on indirect approaches and R-matrix fits of a complicated excitation function, resulting in different central values and widely different error estimates [3,4,5,6]

Summary

Introduction

Experimental nuclear astrophysics aims to understand the origin of the chemical elements by laboratory experiments [1]. Neutrino fluxes are presently better known than the related nuclear reactions of the proton-proton (pp) chain. They have been used to determine the cross sections of two pp-chain nuclear reactions: 3He(α, γ)7Be [8] and 7Be(p,γ)8B [9]. The present contribution describes the progress of the higher-energy underground accelerator in Felsenkeller, Dresden, with a science program that is complementary to LUNA and to the LUNA-MV project

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