# Presentation: 122340

## Study of High-Spin States in 49-51Ti

**Center for Nuclear Study, University of Tokyo**
**Megumi Niikura**

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
Thank you for introduction.
The title of my talk is ‘study of high-spin stats in 49-51Ti.
My name is Megumi Niikura from CNS, University of Tokyo.

## High-spin Study in Neutron-rich Nuclei

- Study of superdeformation in
- A=40-80 region

- 40Ca

- 56Ni

- 36Ar

- 50Ti (Z=22, N=28)

- N=Z

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
This work is motivated to study of high-spin states in neutron-rich nuclei.
General high-spin study, high-spin states is populated by the fusion-evaporation reaction.
Since fusion reaction by the stable isotope beam and target combination can only produce proton-rich side relative to the beta stability line.

This figure 

## Secondary Fusion Reaction

**High-spin study by fusion-evaporation reaction.**
**Stable isotope beam and target combination**
- Proton-rich side
**Using neutron-rich secondary beam**
- High-spin study in neutron-rich nuclei
- _46__Ar(__9__Be,xn)__55-x__Ti_
**For fusion reaction by RI beam**
- Production of low-energy RI beam
- RIPS
- High-efficiency and high-resolution gamma-ray detector
- GRAPE

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
High-spin study is mainly performed by 

## Experimental Setup

- Nuclear reaction : 	46Ar(9Be,xn)55-xTi

- 48Ca primary beam
- 63 A MeV

- GRAPE (Gamma-Ray detector Array with Position and Energy sensitivity

- Rotatable degrader
- Al 0.3mm

- Wedge degrader
- Al 0.6mm

- F2

- Plastic Scintillator

- PPACs

- PPAC

- Secondary target
- 9Be 10um

- Primary target
- 9Be 1.625mm

- F1

- 46Ar

- _RIPS facility at RIKEN_

- Super conducted Triplet
- Quadruple Magnet (STQ)

- Beam image

- Beam energy

- Secondary 46Ar beam
- Beam rate : ~1 Mcps@F3
-         purity : ~95%

- PPAC

- Clover Ge

- 0

- -50

- 0

- 50

- 50

- -50

- (mm)

- 0

- 2

- 4

- 6

- 8

- 10

- (MeV/u)

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Gamma-ray Detector (GRAPE)

-  Consist of 18 planer type Ge, 2 Clover and 1 coaxial Ge.
-  One detector of GRAPE have two Ge crystals.
-  By using pulse shape analysis, position resolution is 5mm.
-  Total efficiency is about 4% for 1MeV  ray.

- Secondary target

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Fusion Event Identification

- 0

- 200

- 0

- 100

- 0

- 200

- -200

- 50

- 0

- 50

- 100

- TOF F2-F3 (ns)

- TOF target-F3c (ns)

- 100

- -100

- 20

- 40

- Ge ARC Timing (ns)

- Counts

- Fusion Residues

- Prompt  ray

- F2 Plastic

- F3 PPAC

- F3 PPACc

- target

- 46Ar beam

- TOF F2-F3

- TOF Tgt-F3c

- x102

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Single Gamma-ray Spectrum

- 46Ar(9Be,xn)55-xTi

- 0

- 1000

- 2000

- 3000

- 4000

- 0

- 2000

- 4000

- 6000

- 8000

- 10000

- Gamma-ray energy (keV)

- Counts par 2keV

- 49Ti

- 50Ti

- 51Ti

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Excitation Function Analysis

- Statistical model calculation

- Experiment

- 46Ar beam energy [MeV/u]

- Cross section [mb]

- Relative intensity

- Beam energy

- 0

- 2

- 4

- 6

- 8

- (MeV/u)

- 51Ti gamma rays

- 49Ti gamma rays

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Relative -ray yield

- 46Ar beam energy [A MeV]

- Relative -ray yield

- 1437

- 1437

- 907

- 907

- 410

- 410

- 888

- 888

- 761

-  As incident beam energy increases, larger angular momentum can brought into the system and consequently a relative population of higher spin states will increases.

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## - coincidence analysis (49Ti)

- 49Ti

- 2665

- 2620

- 2665

- 2620

- Gamma-ray energy [keV]

- 1543+1092 keV gated

- Count par 4 keV

- x10

- 7047

- 7002

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## - coincidence analysis (51Ti)

- - coincidence analysis (51Ti)

- 51Ti

- 761

- 830

- 2490

- (672)

- 4403

- 5233

- x10

- 672

- 761

- 830

- Gamma-ray energy [keV]

- Count par 4 keV

- 907+890 keV gated

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Angular Distribution

- 0

- 50

- 100

- 150

- 0

- 50

- 100

- Angle (deg)

- -ray yield

- x104

- preliminary

- 1437

- 907

- 890

- 761

- 678

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Level Scheme and Shell Model Calculation

- (23/2-)

- (17/2-)

- (11+)

- (21/2-)

- (15/2-)

- Shell model code ; Antoine

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Summary

**We have studied high-spin states in neutron-rich Ti isotopes by secondary fusion reaction, ****46****Ar(****9****Be,xn)****55-x****Ti****.**
**By ********-******** coincidence analysis**** and ****excitation function analysis****, we observed cascade gamma decay from ****(23/2), (11+),**** and ****(17/2)**** states in ****49-51****Ti, respectively.**
**To compare with shell model calculation, we observed the existence of ****1p1h excitation**** in this region, systematically.**

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
最後の文章をどうしようか悩んでます。

## Collaborators

**CNS, University of Tokyo**
**	****E.Ideguchi, S.Shimoura, S.Ota, Y.Wakabayashi, S.Michimasa**
**Dep. Phys., University of Tokyo**
**	****T.Onishi, Y.Ichikawa, H.Suzuki, D.Suzuki, H.Iwasaki**
**Nishina Center, RIKEN**
**	****T.Kubo, K.Yoshida, N.Aoi, T.Ohnishi, H.Baba**
**Dep. Phys., Osaka University**
**	****T.Fukuchi**
**IMPCAS, China**
**	****M.Liu, Y.Zheng****	****	**

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Excitation function analysis

- -ray energy [keV]

- Counts per 4 keV

- 46Ar beam energy [A MeV]

- 0-3.5 A MeV

- 3.5-4.5 A MeV

- 4.5-5.5 A MeV

- 5.5-7.0 A MeV

- -ray spectra by gating different region of the beam energy spectrum.
-  Different isotopes are populated in different beam energy region.

- 1432 (51Ti)

- 1050 (52Ti)

- 1554 (50Ti)

- 1543 (49Ti)

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Angular momentum

- Bass model calculation

- ~12 ħ

- ~24 ħ

- Maximum angular momentum brought in to the reaction products by the fusion reaction.

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
この質量領域での超変形回転バンドの探査には、反応によって生成する原子核に15h以上の大きな角運動量を持ち込む必要があります。
大きな角運動量を反応によって持ち込むためには、重イオン核融合反応が有効です。

図の説明。
これまで、
安定核同士の組み合わせがない。
で、不安定核46Arをつかったこの反応を使った。

## -ray spectrum

- ドップラー補正

- 0

- 90

- 180

- 60

- 120

- 30

- 150

- 0

- 1000

- 2000

- 3000

- 4000

- Angle (deg)

- Gamma-ray energy (keV)

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Statistical Model Calculation (CASCADE)

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
二次反応の断面積に関しては、Cascadeによる統計計算のシュミレーションがあります。
今回の実験では50Tiをターゲットにしていますので、およそ核子あたり4MeV程度のビームエネルギーのときその断面積が最大で、およそ500mb程度になると予想されます。
まずはこの計算結果をもとに実験を行い、励起関数を実験的に測定しました。

## 51Ti shell-model calculation

- f7/2 p3/2 p1/2 f5/2

- 2000 8100 62.3%
- 2000 7200   5.3%

- 2000 8100 56.0%
- 2000 7200  6.8%

- 2000 8100 47.7%
- 2000 7200 14.7%

- 2000 8100   2.6%
- 2000 7200 25.0%

- 2000 8100  <1%
- 2000 7200 47.4%

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## Multiplicity measurements

- 0

- 50

- 100

- 150

- 0

- 50

- 100

- Angle (deg)

- -ray yield

- 2

- 3

- 4

- 5

- Number of hold in Ge

- 2

- 4

- 6

- 8

- -ray relative yield

- x104

- preliminary

- preliminary

- 678

- 761

- 907, 890

- 1437

- 907

- 890

- 761

- 678

- 761

- 678

- (15/2,19/2)

- (17/2,21/2)

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

**Notes:**
このスライドは作り直します。

## Level Scheme and Shell Model Calculation

- 761

- 840

- (15/2)

- (17/2)

- 2000 8100 62.3%
- 2000 7200   5.3%

- 2000 8100 56.0%
- 2000 7200  6.8%

- 2000 8100 47.7%
- 2000 7200 14.7%

- 2000 8100 < 4%
- 2000 7200 47.4%

- 2000 8100   2.6%
- 2000 7200 25.0%

- Proton                Neutron
- f7/2 p3/2 p1/2 f5/2    f7/2 p3/2 p1/2 f5/2

- Shell model code ; Antoine

- 670

- 2204

- 2620

- 2680

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## - coincidence analysis

- 49Ti (1543+960+780keV gated)

- 50Ti (1552+1117+523+2930+232+402+800keV gated)

- 51Ti (1437+907+888keV gated)

- 0

- 400

- 800

- 1200

- 1600

- 2000

- Gamma-ray energy (keV)

- Counts

- 678

- 761

- 0

- 50

- 100

- 0

- 200

- 400

- 0

- 100

- 200

- 150

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## GRAPEの測定回路

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008

## ガンマ線の検出位置

- The 2nd LACM-EFES-JUSTIPEN Workshop

- 24th Jan. 2008