Method to evidence hypernuclear halos from a two-target interaction cross section measurement

Abstract

We present a two-target measurement method to determine the interaction cross section of hypernuclei with a target nucleus. The method allows to extract from two independent measurements the production cross section of a given hypernucleus as well as its interaction cross section on a specific target. The latter is then further analyzed to deduce the matter radius of the hypernucleus. The sensitivity of the method has been investigated for the specific case of the lightest hyperhalo candidate hypertriton ($$^3_\Lambda $$ Λ 3 H) produced from $$^{12}$$ 12 C+$$^{12}$$ 12 C collisions at 1.9 GeV/nucleon. Furthermore, its feasibility is demonstrated by detailed simulations for realistic experimental conditions at GSI/FAIR, using a dedicated HYDRA (HYpernuclei Decay at R$$^3$$ 3 B Apparatus) time-projection chamber prototype. A precision of 15% or better in the interaction cross section can be achieved, allowing an extraction of the unknown $$^3_\Lambda $$ Λ 3 H matter radius and assessing its halo or non-halo character.

Nuclear structure opportunities with GeV radioactive beams at FAIR

“…The large inner gap of GLAD allows, in some cases, placing the reaction targets directly inside the spectrometer, for example, in future experiments dedicated to hypernuclei [36]. In the standard R 3 B configuration, the target is positioned directly in front of GLAD, inside a vacuum chamber surrounded by the CALIFA calorimeter (CALorimeter for the In-Flight detection of γ -rays and light-charged pArticles) [33,34], as shown in the inset of figure 1.…”

“…The measurement is a 'hyper' version of the historical Berkeley experiment that led to the discovery of halo nuclei. Based on a new experimental method [36], the interaction cross-section will be determined, allowing extraction of the unknown hypertriton matter radius and providing an unambiguous conclusion on its halo or non-halo character. The extracted matter radius will be key information on the structure of the hypertriton.…”