abc In-beam gamma-ray spectroscopy of 36,38 Mg Pieter Doornenbal - PowerPoint PPT Presentation

abc

In-beam gamma-ray spectroscopy of 36,38 Mg Pieter Doornenbal ピ ー タ ー ドルネンバル

Outline ● Motivation The “Island of Inversion” Experimental Setup ✦ The “Island of Inversion” Results ✦ Present experimental status Summary and Outlook ● Experimental setup ✦ RIB selection and identification with BigRIPS/ZDS ✦ Gamma-ray detection with DALI2 ● Results ✦ E (4 + 1 ) and E (2 + 1 ) in 36,38 Mg ARIS Conference, May 30 th – June 3 rd , 2011 – 3 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

The “Island of Inversion” ARIS Conference, May 30 th – June 3 rd , 2011 – 4 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Nuclear Chart stable isotopes (300) known isotopes (3000) isotopes estimated to exist (6000) 184 number of protons 162 82 Pb 126 Island of Inversion 50 Sn ● Neutron-rich Ne, Na, Mg iso- topes near N = 20 82 28 Ni ● Vanishing N = 20 shell closure ● Rapid changes in nuclear struc- ture 50 ● 48 Ca beam at 345 MeV/ u 28 20 ● High intensity > 100 pnA number of neutrons 2 8 ARIS Conference, May 30 th – June 3 rd , 2011 – 5 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

The “Island of Inversion” 30 Si 31 Si 32 Si 33 Si 34 Si 35 Si 36 Si 37 Si 38 Si Z = 14 The “Island of 215(10) 113(33) 84(33) 190(60) 190(70) Inversion” + + ) ? 3 ( 3 ( 7 ? 2235 2.4 1942 (2.7) 3328 (1.0) 1399 ? − ) 1084 ? 2 2 2 2 ❖ Nuclear Chart 5280 (5220) ? ? ? ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ ❖ Shell Structure 29 Al 30 Al 31 Al 32 Al 33 Al 34 Al 35 Al 36 Al 37 Al Signatures + ? ? 5 ( 3 2 , 5 2 ) + ( 3 2 ) + ? ? 3 + 1 + ? ? ? ? 2 2 2 Experimental Setup ◦ ◦ ◦ ◦ • ◦ ◦ • ◦ ◦ ◦ Results 28 Mg 29 Mg 30 Mg 31 Mg 32 Mg 33 Mg 34 Mg 35 Mg 36 Mg Z = 12 38 Mg 350(50) 270(16) 413(29) 631(126) ? Summary and + (+) ? 3 1 ? ( 7 (1.2) (3.2) 660(6) 1473 2.7 1482 885 2.6 670 − ) ? 2 2 2 2 Outlook 4020 (1789) 2322 (2120) ? ◦ ◦ ◦ • • • • • • 27 Na 28 Na 29 Na 30 Na 31 Na 32 Na 33 Na 34 Na 35 Na + + + 2 ) + ? 5 3 3 ( 3 ? 1 + 2 + ? ? (3 , 4) − 2 2 2 2 ◦ ◦ ◦ • • • • 26 Ne 27 Ne 28 Ne 29 Ne 30 Ne 31 Ne 32 Ne 33 Ne 34 Ne Z = 10 228(41) 270(14) ? ? ? even-even + ) + ) ? ? ( 3 ( 3 ? ? 792(4) (2.8) 722(9) 2018 ? 1310 ? ? ? ? 2 2 2 2 (2235) ? ? ? ? B ( E 2 ↑ ) ◦ ◦ ◦ • • E (4 + 1 ) E (2 + 1 ) 25 F 26 F 27 F 28 F 29 F 30 F 31 F 32 F 33 F E (2 + 1 ) E (4 + 1 ) + ) + ) + ) ? ? ( 5 ( 5 ( 5 ? ? 1 + ? ? ? ? ? ? 2 2 2 2 2 ◦ ◦ ◦ N = 16 N = 18 N = 20 N = 22 N = 24 PD, H. Scheit et al. , PRL 103 , 032501 (2009) A. Gade et al. , PRC 83 , 044305 (2011) A. Gade et al. , PRL 99 , 072502 (2007) ARIS Conference, May 30 th – June 3 rd , 2011 – 6 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Experimental Shell Structure Signatures 3500 Z=16 (S) Z=14 (Si) 3000 Z=12 (Mg) Z=10 (Ne) 2500 + ) (keV) 2000 E(2 1 1500 1000 500 0 14 16 18 20 22 24 26 Neutron number ARIS Conference, May 30 th – June 3 rd , 2011 – 7 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Experimental Setup ARIS Conference, May 30 th – June 3 rd , 2011 – 8 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

BigRIPS Overview second stage first stage Production Target Big RI KEN P rojectile Fragment S eparator ● Two stage separator ✦ 1 st : separation ✦ 2 nd : identification, further separation ● Large acceptance (80 mr, 100 mr, 6 %) ✦ projectile fragmentation ✦ in-flight fission of U Bρ max = 9 Tm L ∼ 77m P/ ∆ P ∼ 1300(1st) 3300(2nd) ARIS Conference, May 30 th – June 3 rd , 2011 – 9 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

ZeroDegree Spectrometer 2 nd BigRIPS stage secondary target ∼ 3 m between Q-poles ● DALI2 array, 186 NaI(Tl) 0 ◦ Spectrometer ZeroDegree ● GRAPE HPGe array ● particle ID after secondary target ● fragment momentum distribution ● E beam ∼ 100 − 250 ● various modes of operation MeV/ u mode p/ ∆ p ∆ p Ang. Accep. Large Accep. 1240 ± 3 % ± 45 mrad(V) ± 30 mrad(H) High res.(achrom) 2120 ± 3 % ± 20 mrad(V) ± 30 mrad(H) Dispersive 4130 ± 2 % ± 20 mrad(V) ± 30 mrad(H) ARIS Conference, May 30 th – June 3 rd , 2011 – 10 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

DALI2 ● 186 NaI(Tl) detectors The “Island of Inversion” ● ϑ coverage 11 ◦ to 165 ◦ Experimental Setup ❖ BigRIPS Overview ● ∆ E/E ≈ 10(11) % (FWHM) at 100(250) MeV/ u ❖ ZeroDegree ❖ DALI2 ● ≈ 20% FEP efficiency at 1 MeV Results Summary and ● Thick targets, 2.54 g/cm 2 C, 2.13 g/cm 2 CH 2 , 3.37 Outlook g/cm 2 Pb ● S. Takeuchi et al. , RIKEN Pr. Rep. 36, 148 (2003) ARIS Conference, May 30 th – June 3 rd , 2011 – 11 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Results ARIS Conference, May 30 th – June 3 rd , 2011 – 12 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

PID in Front of Secondary Target The “Island of Inversion” 16 Charge Q 40 Experimental Setup 3 Si 10 15 Results ❖ PID 2 10 ❖ PID Behind Target 14 39 Al ❖ Level Structure in Mg 10 13 Summary and Outlook 12 1 2.8 2.85 2.9 2.95 3 3.05 Mass to Charge Ratio A/Q ● ∆ E − Bρ − TOF method ✦ Z ∝ ∆ E ∆ Z = 0 . 33 (FWHM) ✦ A/Q ∝ TOF ∆ A = 0 . 08 (FWHM) ● 40 Si: 3000/s E ≈ 230 MeV /u ● 39 Al: 100/s E ≈ 215 MeV /u ARIS Conference, May 30 th – June 3 rd , 2011 – 13 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

PID Behind Target and γ -ray Spectra PID after F8 Doppler corrected γ -ray energy 14 Charge Q C( 40 Si, 38 Mg * ) 10 13 20 g.s. 0 + Counts / 20 keV 15 12 1 ) (2 + 1 10 4 + 11 1 ? -1 5 10 10 2.9 3 3.1 3.2 3.3 0 Mass to Charge Ratio A/Q C( 39 Al, 38 Mg * ) 20 ● 48 Ca, 70 pnA primary beam g.s. 0 + Counts / 20 keV ● C( 40 Si, 38 Mg * ), C( 39 Al, 38 Mg * ) 15 1 ) (2 + ● 40 Si: 3000 pps, 230 MeV/ u 10 ● F8 target: nat. C, 2.54 g/cm 2 5 ● E (2 + 1 ) at 660(10) keV 0 ● Total data taking: 14.7 hours 0 500 1000 1500 2000 2500 E γ (keV) ARIS Conference, May 30 th – June 3 rd , 2011 – 14 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Level Structure of Neutron-Rich Magnesium Isotopes The “Island of 3 3 Utsuno Inversion” Caurier Nowacki Experimental Setup (4 + ) (4 + ) (4 + ) (4 + ) (4 + ) (4 + ) (4 + ) (4 + ) Results 2 2 ❖ PID ❖ PID Behind Target ❖ Level Structure in E x (MeV) E x (MeV) Mg 2 + 2 + 1 1 Summary and 2 + 2 + 2 + 2 + (2 + ) (2 + ) Outlook 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 0 A=32 A=32 34 34 36 36 38 38 ● E (4 + 1 ) / E (2 + 1 ) ≈ 3 . 1 for A = 34 − 38 Y. Utsuno et al. , PRL 60 , 04315 (1999) E. Caurier et al. , NPA 693 , 374 (2001) . Nowacki and A. Poves, PRC 79 , 014310 (2009) F ARIS Conference, May 30 th – June 3 rd , 2011 – 15 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Summary and Outlook ARIS Conference, May 30 th – June 3 rd , 2011 – 16 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Summary and Outlook The “Island of ● Found new excited states in 18 nuclei within 2.5 days of Inversion” beam time Experimental Setup Results ● E (2 + 1 ) of 38 Mg at low energy Summary and Outlook ❖ Summary ❖ Collaboration ● E (4 + 1 ) / E (2 + 1 ) ≈ 3.1 for 34-38 Mg ● Preliminary results, analysis ongoing ARIS Conference, May 30 th – June 3 rd , 2011 – 17 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

Collaboration The “Island of Inversion” Experimental Setup Results Summary and Outlook ❖ Summary ❖ Collaboration ARIS Conference, May 30 th – June 3 rd , 2011 – 18 PD, In-beam gamma-ray spectroscopy of 36,38 Mg

THE END ARIS Conference, May 30 th – June 3 rd , 2011 – 19 PD, In-beam gamma-ray spectroscopy of 36,38 Mg