Publications
Publication Information
| Title | A Possible Observation of Lambda-nn Continuum Structures and A Bound Sigma-NN State Using the (e, e'K+) Reaction |
| Authors | Bishnu Pandey |
| JLAB number | JLAB-PHY-21-3364 |
| LANL number | (None) |
| Other number | DOE/OR/23177-5183 |
| Document Type(s) | (Thesis) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
|
Thesis A PHD thesis Advisor(s) : Liguang Tang (JLAB) | |
| Publication Abstract: | The E12-17-003 (e,e'K+) experiment was carried out in the experimental Hall A facility of Jefferson Lab in November 2018. The experiment aimed at providing the experimental data for the unknown Lambda-n interaction by measuring the bound state or the resonance state as indicated by the HypHI experiment. The so obtained Lambda-n interaction was assumed to solve the existing charge symmetry breaking problem in the case of Lambda-N interaction. The experiment used Hall A high resolution spectrometers (both left and right spectrometers) positioned symmetrically at constant angle 13.2 deg. each. A 25 cm long aluminum cylinder filled with H-3 gas was used as a production target. The major calibration data were taken with the H target contained in an identical aluminum cylinder. The electroproduction of Lambda and Sigma^0 via p(e, e'K+)Lambda, Sigma^0 reactions was used to calibrate the absolute energy scale with the known masses of the Lambda and Sigma^0. Then by using the (e, e'K+) Sigma-reaction, two possible Lambda-nn resonance states and one NN bound state were observed. The observed states have the energy resolution about 1.6 MeV (FWHM), however, great r statistics are required to solidly confirm the observed states. The A = 3 and 4 Sigma bound states have been predicted long ago but only the A = 4 Sigma hypernucleus, that is He-4/Sigma, was found in the (K-, pi-) reaction. A careful Monte Carlo study was conducted to study the A (nuclear mass number) dependence on the missing mass resolution by using the identical experimental conditions. The simulated and experimentally obtained Lambda and Sigma^0 channels agreed within 100 keV in sigma, where sigma is the standard deviation. The intrinsic missing mass resolution of A = 3 (3/Lambda-n) resonance was predicted about sigma = 0.67 MeV with a natural width of about 0.6 MeV. However, due to the low statistics the precision does not permit sufficient constrain on the determination of the Lambda-n interaction. The reason of having such low statistics is due to the use of unoptimized Hall A system which was definitely feasible but not ideal for this experiment. In addition, the cross section was found to be much smaller than expected. |
| Experiment Numbers: | E12-17-003 |
| Group: | Hall A |
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| DOI: | |
| Accepted Manuscript: | |
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