# Presentation: 474172

## Spectroscopy of Light to Medium Mass Lambda Hypernuclei

**Jefferson Lab Experiment E01-011**

- Joerg Reinhold
- Florida International University
- presented at
- PANIC05
- October 24, 2005

## Hypernuclear Spectroscopy

- No Pauli blocking ==> probing deep inside the nucleus
- Narrow intrinsic width (~100 keV)
-  single particle energies in excitation range of more than 20 MeV
- Spin dependent -N interactions (s.s. & s.o.) much weaker than N-N case

- What to learn
- Hyperon nucleon interaction, i.e. at low momentum
- Spin dependent interactions
- L effective mass and potential depth in the nuclear medium
- Identity of  as function of A

- Hypernucleus: one or more nucleons replaced by a hyperon,  ,  or 

- H. Hotchi, et al., Phys. Rev. C64, 044302 (2001)

## 12C(p+,K+)12C

- P.H. Pile, et al., Phys. Rev. Lett. 66, 2585 (1991)

- T. Hasegawa, et al., Phys. Rev. C53, 1210 (1996)

- KEK
- DE = 2 MeV (FWHM)

- BNL
- DE = 3 MeV (FWHM)

- 12C(p+,K+)12C

- Previous  Hypernuclear Spectroscopyestablished major shell structure

## Experimental Considerations

- High resolution spectrometers at low momentum

## E89-009 Results T. Miyoshi, et al., PRL90, 232502 (2003)

- E89-009 Results T. Miyoshi, et al., PRL90, 232502 (2003)

- Theoretical line is a superposition(not a fit) with strength from [19] and positions from[20].

## New Jlab E01-011 ExperimentSpectroscopic study of  hypernuclei up to the medium heavy mass region by the (e,e’K+) reaction

- Yamagata University
- KEK
- Osaka EC University
- Hampton University
- Florida International U.
- Houston University
- TJNAF

- North Carolina A&T U.
-  Minnesota University
- Louisiana Tech. U.
- Yerevan Physics Institute
- University of Zagreb
- University of Bucharest
- University of Sao Paulo

- New Jlab E01-011 ExperimentSpectroscopic study of  hypernuclei up to the medium heavy mass region by the (e,e’K+) reaction

## Experimental Setup

## Tilt method for ENGE to reduce the accidental rate  

- Locate ENGE
- with _7.74 degree._
- _to avoid (1) and (2) _
- _processes.  _

- Scattered electrons
-      (0.2 to 0.4 GeV/c)
- (1) Bremsstrahlung
- (2) Møller scattering
- (3) Virtual photons

## Optimization of the tilt angle

**Side view**

- Accept region.

## Tilted ENGE (e-) Spectrometer

## HKS + ENGE + Splitter 

- ENGE

- HKS

- Splitter

## Expected Energy Resolution

| Item | Contribution to the resolution (keV, FWHM) |  |  |  |  |
| --- | --- | --- | --- | --- | --- |
| Target | 12C | 28Si | 51V | 89Y |  |
| HKS momentum | 230 |  |  |  |  |
| Beam momentum | < 180 |  |  |  |  |
| Enge momentum | 120 |  |  |  |  |
| K+ angle | 134 | 56 | 32 |  | 18 |
| Target thickness | < 180 | < 171 | < 148 |  | < 138 |
| Overall | < 390 | < 360 | < 350 |  | < 345 |

**~400 keV **

## Trigger condition

- HKS (Kaon trigger) --- 12 kHz
-       - 1X & 1Y & 2X & AC & WC
-                 AC -pion rejection, WC -proton rejection
-       ( 1X - 2X -1.1 MHz )
- ENGE --- 1.2 MHz
-      Hodoscope 1layer & 2layer
- Coincidence trigger
-           ~500 Hz
-           DAQ dead time ~5%
-    *Rates are with carbon target (100 mg) , 26 A

**1X  1Y           AC        2X  WC**

**K****+**

**HKS arm**

## Calibration: CH2(e,eK)

**210 lambdas                                        1390 lambdas**

- HNSS 2000

- HKS 2005

## 12C(e,eK)12Bwith imperfect on-line reconstruction

- On-line Preliminary

- Do not quote!

- ~1000 counts in g.s.
- (full set ~ 2500 in g.s.

## 28Si(e,e’K)tracking algorithm and reconstruction matrix NOT optimized

- On-line Preliminary

- Do not quote!

- 28Si(e,e’K)tracking algorithm and reconstruction matrix NOT optimized

## Summary

-  Precision analysis of core excited states
-  p-orbit states splitting ?
-  comparison with the mirror hypernucleus, 12C
-  28Si  12Al  (expected up to 1000 counts in g.s.)
- The first precision spectroscopy beyond the p-shell
*ls* splitting in the p, d orbits ?
-  Other targets (6Li, 9Be, 10B, 51V, 89Y)
-   Rate study for heavier targets, new experiment for 51V approved
-   p-shell spectroscopy
-   Target mass dependence --- quasifree K+                                     					    electroproduction