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Project List » Direct measurements of Nuclear Astrophysics at IFIN-HH

Direct measurements of Nuclear Astrophysics at IFIN-HH

Acronym: NUCASTRO2
Contracting Authority: Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI)
Number / Date of the contract: PN-III-P4-ID-PCE-2016-0743 / 2017-09-08
Project Manager: Livius Trache
Starting date / finishing date: 2017-09-08 / 2019-12-31
Project value: 775700 RON
Abstract: Nuclear astrophysics (NA) is currently an important part of the scientific program of all large or small, existing or planned, nuclear physics facilities in Europe and elsewhere. NA, or more exactly Nuclear Physics for Astrophysics (NPA) aims at providing data and models for the understanding of the origin of the chemical elements in the Universe. We are far from having a complete quantitative explanation of the creation of elements, in spite of many successes in the last decades. More nuclear data are needed at energies appropriate for stellar processes.
In June 2012 the project director has returned from a large laboratory in the USA (Cyclotron Institute, Texas A&M University, College Station) after a two decades stay and has applied for a grant to start a nuclear astrophysics group (NAG) at IFIN-HH. The grant proposal PNII-ID-PCE-2012-4-0299 "Nuclear astrophysics studies at IFIN-HH - NUCASTRO" was successful (98 pcts. out of 100) and financing was provided for 3 years: Oct 2013 - Sep 2016. The work originally proposed was in large part a continuation of the work done prior, combining experimental work to be done in IFIN-HH and at reputed foreign user facilities, with accent on nuclear astrophysics with indirect methods. A group and a plan were initiated and successfully implemented (to my opinion), given the local conditions and financing. However, once on ground at IFIN-HH in Magurele, new possibilities seemed to occur: the possibility to do competitive direct measurements for nuclear astrophysics.
Indeed, we demonstrated that we have good conditions to make such direct measurements for nuclear astrophysics, in particular α-induced reactions and reactions between light ions. The institute has a new 3 MV tandetron, installed in 2012 and which works since mid 2013 for applications and for NA [1]. Since the beginning of its operation we tested its capabilities for such direct measurements: appropriate energy range, stability, diversity of projectiles, high currents. We tested all of the above and found the it will be competitive. The energies are given by the terminal voltage range which is V=0.3 - 3.3 MV. It was tested to be stable over weeks of operation. It has two ion sources: a duoplasmatron and a sputter source. Na, Cs and Li charge exchange are used preferentially. These allow a diversity of beams to be provided.
An extra opportunity is provided by the ultra-low background laboratory the institute has underground in a salt mine located at about 100 km north of Bucharest, in Slanic-Prahova [2], named μBq (MicroBequerel) laboratory. While at about 260 m below surface this is not a particularly deep mine, it has the property of being very low in natural radioactivity, due to a large distance from rocks and its compact salt walls. With a well shielded Ge detector a background reduction factor up to 4000 was obtained (relative to the surface background of the same unshielded detector).
We have, therefore, tested a procedure in which we irradiate targets in Magurele, then transfer them in Slanic and measure them. Obviously this procedure will not work for cases where the resulting activity after irradiation has half-lives much shorter than the transfer time of about 2.5 hrs. One case ideal for the test of the procedure was the reaction 13C+12C. This was a joint proposal with a group from IMP Lanzhou, China. We could reach into the Gamow window (measurements in Sept.-Oct. 2014 and in Oct. 2015), to cross sections of the order of tens of picobarns, about 100 times more sensitive than any measurement done before (at the Notre Dame University, USA).

We concluded that this laboratory can be competitive for direct nuclear astrophysics measurements induced by alpha particles and light ions. We intend to further use these findings and strengthen them on cases that can use this combination of facilities. For now we want to propose a program that goes on two distinct lines:
- Continue the study of reactions between light ions like 12C and 16O down into the Gamow window or as close as possible to it;
- Start a program using α-beams to measure α-induced reactions on proton rich nuclei. Selection at this point is being done for reactions that produce activations that are long enough for the targets to be transferred to Slanic.

The NAG group has identified two alpha-induced reactions for the first phase: 58Ni(α,?)62Zn and 64Zn(α,p)67Ga. We plan to measure for the energy range Eα=5-9 MeV with steps of 0.2 and 0.5 MeV. In the experiments we will (i) measure prompt gamma-rays (as far down in projectile energy as we could) to assess the contribution of all open reaction channels and (ii) do activation measurements. These latter are the most sensitive when we use the ultra-low background salt mine laboratory.

They have been proposed to the latest session of the PAC and have been approved. They will be part of the thesis program for two of the students of the group. However, the group does not have financing for the 4 students involved in the program, and this proposal seeks the necessary means (salaries and consumables).
Prompt gamma-ray measurements will be done with two new n-type HpGe detectors (70% relative efficiency) in Magurele and with a larger 120% HpGe detector at μBq. A beta-gamma coincidence setup will be made in Magurele for de-activation measurements in IFIN-HH. A 9 MV tandem also exists in the institute, well equipped for gamma-rays and particle detection, where we could extend measurements at higher energies, if needed.
Research Group webpage


1.  (2017-12-27) Results
2.  (2018-12-31) Results
3.  (2019-12-31) Results
RESULTS [Project Activity Report]

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