[Bubble] more competition

[Jay Benesch]

https://arxiv.org/abs/1810.08201

The new Felsenkeller 5 MV underground accelerator
Daniel Bemmerer, Thomas E. Cowan, Toralf Döring, Marcel Grieger, 
Sebastian Hammer, Thomas Hensel, Lisa Hübinger, Arnd R. Junghans, Felix 
Ludwig, Stefan E. Müller, Stefan Reinicke, Bernd Rimarzig, Konrad 
Schmidt, Ronald Schwengner, Klaus Stöckel, Tamás Szücs, Steffen Turkat, 
Andreas Wagner, Louis Wagner, Kai Zuber
(Submitted on 18 Oct 2018)

     The field of nuclear astrophysics is devoted to the study of the 
creation of the chemical elements. By nature, it is deeply intertwined 
with the physics of the Sun. The nuclear reactions of the proton-proton 
cycle of hydrogen burning, including the 3He({\alpha},{\gamma})7Be 
reaction, provide the necessary nuclear energy to prevent the 
gravitational collapse of the Sun and give rise to the by now 
well-studied pp, 7Be, and 8B solar neutrinos. The not yet measured flux 
of 13N, 15O, and 17F neutrinos from the carbon-nitrogen-oxygen cycle is 
affected in rate by the 14N(p,{\gamma})15O reaction and in emission 
profile by the 12C(p,{\gamma})13N reaction. The nucleosynthetic output 
of the subsequent phase in stellar evolution, helium burning, is 
controlled by the 12C({\alpha},{\gamma})16O reaction.
     In order to properly interpret the existing and upcoming solar 
neutrino data, precise nuclear physics information is needed. For 
nuclear reactions between light, stable nuclei, the best available 
technique are experiments with small ion accelerators in underground, 
low-background settings. The pioneering work in this regard has been 
done by the LUNA collaboration at Gran Sasso/Italy, using a 0.4 MV 
accelerator.
     The present contribution reports on a higher-energy, 5.0 MV, 
underground accelerator in the Felsenkeller underground site in 
Dresden/Germany. Results from {\gamma}-ray, neutron, and muon background 
measurements in the Felsenkeller underground site in Dresden, Germany, 
show that the background conditions are satisfactory for nuclear 
astrophysics purposes. The accelerator is in the commissioning phase and 
will provide intense, up to 50{\mu}A, beams of 1H+, 4He+ , and 12C+ 
ions, enabling research on astrophysically relevant nuclear reactions 
with unprecedented sensitivity.

Comments: 	Submitted to the Proceedings of the 5th International Solar 
Neutrino Conference, Dresden/Germany, 11-14 June 2018, to appear on 
World Scientific
Subjects: 	Accelerator Physics (physics.acc-ph); Nuclear Experiment 
(nucl-ex); Instrumentation and Detectors (physics.ins-det)