Progress of Jinping Underground laboratory for Nuclear Astrophysics(JUNA)

Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of^(25)Mg(p,γ)^(26)Al,^(19)F(p,α)^(16)O,^(13)C(α,n)^(16)O and ^(12)C(α,γ)^(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.

A proposed direct measurement of cross section at Gamow window for key reaction 19F(p,α) 16O in Asymptotic Giant Branch stars with a planned accelerator in CJPL

In 2014, the National Natural Science Foundation of China(NSFC) approved the Jinping Underground Nuclear Astrophysics laboratory(JUNA) project, which aims at direct cross-section measurements of four key stellar nuclear reactions right down to the Gamow windows. In order to solve the observed fluorine overabundances in Asymptotic Giant Branch(AGB) stars, measuring the key ^(19)F( p,α)^(16)O reaction at effective burning energies(i.e., at Gamow window) is established as one of the scientific research sub-projects. The present paper describes this sub-project in details, including motivation, status, experimental setup, yield and background estimation, aboveground test, as well as other relevant reactions.

Genomic basis of evolutionary adaptation in a warm-blooded fish

Few fishes have evolved elevated body temperatures compared with ambient temperatures,and only in opah(Lampris spp)is the entire body affected.To understand the molecular basis of endothermy,we analyzed the opah genome and identified 23 genes with convergent amino acid substitutions across fish,birds,and mammals,including slc8b1,which encodes the mitochondrial Na+/Ca2+exchanger and is essential for heart function andmetabolic heat production.Among endothermic fishes,44 convergent genes with suggestive metabolic functions were identified,such as glrx3,encoding a crucial protein for hemoglobin maturation.Numerous genes involved in the production and retention of metabolic heat were also found to be under positive selection.Analyses of opah’s unique inner-heat-producing pectoral muscle layer(PMI),an evolutionary key innovation,revealed that many proteins were co-opted from dorsal swimming muscles for thermogenesis and oxidative phosphorylation.Thus,the opah genome provides valuable resources and opportunities to uncover the genetic basis of thermal adaptations in fish.

A method for determination of deuterium impurity in the helium beam

Both the LUNA(Laboratory for Underground Nuclear Astrophysics)collaboration in Europe and the JUNA(Jinping Underground Laboratory for Nuclear Astrophysics)collaboration in China are planning to study the key reactions during the stellar helium burning at or close to their stellar energies in deep underground laboratories[1-3].The success of such experiments relies on the ratio of the reaction