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HALIMA: Anovel Hybrid Array for nuclear structure research

01.03.26 | Nuclear Science and Techniques

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The principle of two kinds of primary coincidence technique in the present work.
The principle of two kinds of primary coincidence technique in the present work. (a) Fission fragments-γ1-γ2-γ3coincidence method: An isomer is implanted into solar cells, followed by isomeric decay with triple or more γ rays. (b) β-γ1-γ2-γ3coincidence method: A β decay is measured by fast plastic scintillators, followed by a cascade γ ray transition. The feeder (γ2) and decay (γ3) of excited state of interest represented by τ (orange) are detected by LaBr3(Ce), while the precursor transition (γ Credit: Wei Hua

Researchers from the Institute of Modern Physics and collaborating institutions have developed a novel hybrid detection system, named HALIMA, for lifetime measurement. Published in Nuclear Science and Techniques , their work introduces the characteristics of all kinds of instruments in HALIMA, enabling precise sub-nanosecond lifetime measurements of neutron-rich nuclear excited states using the four-fold FF/β-Ge-LaBr 3 (Ce)-LaBr 3 (Ce) coincidence technique.

CsI(Tl)-shielded LaBr 3 (Ce) detection system
To reduce Compton continuums, a more cost-effective, compact and novel CsI(Tl)-based anti-Compton shield was developed. Each LaBr 3 (Ce) detector is enclosed by a CsI(Tl) anti-Compton shield composed of four separated CsI(Tl) crystals. The signals of these crystals are read out using silicon photomultipliers(SiPMs). The employment of CsI(Tl) anti-Compton shields enhances the peak-to-total ratio by a factor of 1.5.

Enhanced selectivity via fission fragments(FFs) implantation
In the present work, a solar cell array was used as FFs detectors. Following fission, the recoiling FF traversed 8 cm and was detected by solar cells. In this configuration, the solar cells act as implantation detectors, enabling event-by-event correlation between FFs and associated γ rays. With this great selectivity, isomer-specific events were effectively selected, and the overwhelming background was significantly suppressed.

Precise lifetime measurement of neutron-rich nuclear excited states
The lifetimes of three excited nuclear states in 134 Te, 138 Ba and 132 Te were measured by applying FF/β-Ge-LaBr 3 (Ce)-LaBr 3 (Ce) coincidence methods, covering a range from a few picoseconds to several hundred nanoseconds. The results were in good agreement with the literature values, demonstrating the capability and precision of this setup.

The research was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Guangdong Province, China, the International Atomic Energy Agency Coordinated Research Project F41034, the computational resources from Sun Yat-sen University the National Supercomputer Center in Guangzhou, the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology, the Central Government Guidance Funds for Local Scientiffc and Technological Development, China, the Guangdong Major Project of Basic and Applied Basic Research, Young Scientists Fund of the National Natural Science Foundation of China and the National Key Research and Development Program. Data and methodology are openly accessible to foster global collaboration in nuclear science.

the complete study is via by DOI: 10.1007/s41365-025-01830-0

Nuclear Science and Techniques

10.1007/s41365-025-01830-0

Experimental study

Not applicable

HALIMA: a hybrid array for lifetime measurement of neutron-rich nuclei at IMP

3-Jan-2026

Additional Media

The γ-γ coincidence matrix of LaBr3(Ce) obtained using M(FFs)-γ-γ-γ coincidence technique shown in the top panel.
The γ-γ coincidence matrix of LaBr3(Ce) obtained using M(FFs)-γ-γ-γ coincidence technique shown in the top panel. The bottom panel shows the time difference distributionsfor the delayed and anti-delayed of 21+states of the132Te. The mean lifetime was determined to be 9(7) ps using the Generalized Centroid Difference (GCD) method, consistent with the literature value of 5(3) ps. Credit: Wei Hua
Photograph of the HALIMA setup at the Institute of Modern Physics (IMP)
(a) Photograph of the HALIMA setup at the Institute of Modern Physics (IMP). Eight HPGe detectors are mounted on the central ring in a horizontal configuration. Two of thethree rings of the LaBr3(Ce) detectors are also visible. The digital data acquisition system and high-voltage supply are located behind the array. (b)Technical schematic of the complete HALIMA setup. Credit: Wei Hua
The energy projection spectra of the symmetric γ-γ coincidence matrix of LaBr3(Ce) detectors obtained using 152Eu standardized source.
The energy projection spectra of the symmetric γ-γ coincidence matrix of LaBr3(Ce) detectors obtained using152Eu standardized source. Compared to the spectrum without CsI(Tl) anti-Compton shields (blue), the background continuums are effectively reduced with the use of CsI(Tl) anti-Compton shields in the energy spectrum (red). Credit: Wei Hua
The energy projection spectra of LaBr3(Ce) demonstrated in three different coincidence methods:
The energy projection spectra of LaBr3(Ce) demonstrated in three different coincidence methods: (1) Ge-LaBr3(Ce))-LaBr3(Ce) (blue); (2) Ge-LaBr3(Ce)-LaBr3(Ce)-solar (red); (3) Ge-LaBr3(Ce)-LaBr3(Ce)-Msolar (black), where Msolar denotes a gate on specific mass of FFs. The 1279 keV are shown in the inset. The peak-to-background ratio of 1279 keV was measured under these conditions. With gating on specific mass of134Te, the peak-to-background ratio of 1279 keV is increased by more than a factor of Credit: Wei Hua

Keywords

Energy Experimental Physics Particle Physics Phases Of Matter Physical Sciences Theoretical Physics

Article Information

Journal
Nuclear Science and Techniques
DOI
10.1007/s41365-025-01830-0
Method of Research
Experimental study
Subject of Research
Not applicable
Article Publication Date
2026-01-03
Article Title
HALIMA: a hybrid array for lifetime measurement of neutron-rich nuclei at IMP

Contact Information

Lihua Sun
Nuclear Science and Techniques (NST)
nst@sinap.ac.cn

Source

Original Source
https://link.springer.com/article/10.1007/s41365-025-01830-0

How to Cite This Article

APA:
Nuclear Science and Techniques. (2026, January 3). HALIMA: Anovel Hybrid Array for nuclear structure research. Brightsurf News. https://www.brightsurf.com/news/L3RGXJ08/halima-anovel-hybrid-array-for-nuclear-structure-research.html
MLA:
"HALIMA: Anovel Hybrid Array for nuclear structure research." Brightsurf News, Jan. 3 2026, https://www.brightsurf.com/news/L3RGXJ08/halima-anovel-hybrid-array-for-nuclear-structure-research.html.