Tests of Solid Targets for Astrophysics Research

(published April 2024)

Realization of ultra-pure material targets is the first of the STAR task goals, to allow for the measurement of low reaction yields, in which signals from parasitic reactions on impurities can limit experiments and must therefore be avoided.

In the STAR framework, targets are produced at LNS-INFN as well as at IFIN-HH (where also PLD and methallotermic reduction are available) via ion implantation, PVD methods (resistive heating and electron beam-based systems), cold rolling and tablet pressing techniques. Moreover, PVD is also available at LNL-INFN, while the University of Cologne laboratory can produce targets by PVD, electrolysis and cold rolling.

Standardized testing of the produced targets has been implemented and it is performed via radioactive sources and/or beam bombardment, and was also offered as a service for the community, including contaminant identification and stability tests.

Here we report about the target already tested under radioactive sources or beam bombardment, while details and further information are being prepared to be published in scientific journals.

@IFIN-HH (NAG group)

Reaction to studyCompoundThicknessBeam/source usedResults
13C+16O13C on Ta backing130 and 150 nm16O beamOk for single irradiation of ~10 mC
13C+16OCeO2 on Al backing0.8 and 1 g/cm213COk for single irradiation of ~10 mC
13C+16OTa2O5150 and 380 nm, with Ta backings of 0.25 and 0.02 mm respectively13CTa2O5 layer disappeared during irradiation. Further studies are needed.
13C+19FLiF1 mm13COk but outgassing
13C+19FBa2F1 mm13COk but very fragile

@LNS-INFN (AsFiN group)

Reaction to studyCompoundThicknessBeam/source usedResults
Fluorine background in New Jedi experimentCaF2 on graphite backing150 μg/cm2 + 30 μg/cm2 (backing)241Am α-sourceNo damage reported
1 mg/cm2241Am α-source @LNS and proton beam @UFJ-NPIResisted up to 200 nA of proton beam


Reaction to studyCompoundThicknessBeam/source usedResults
16O(p,γ)17FTa2O5SeveralProton beamOk and regular areal density profile

These results testify how STAR has gathered European target laboratories in a context where they can learn from mutual experiences and cooperate for the first time.