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22 Na+p 共振散射的厚靶实验研究 原子能院核天体物理组 2013 年 RIBLL 实验计划 王 友 宝
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Contents Scientific Motivation CRIB experiment and result RIBLL experiment
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Orgueuil meteorites and Ne-E problem Fell on May 14, 1864, a few minutes after 8 pm, near Orgueuil in southern France. About 20 stones fell over an area of several square miles. In 1972 , Black found that in Orgueuil meteorites the abundance ratio of 20 Ne/ 22 Ne is less than 1.5 , much lower than that of 9.8 on earth, this is the so-called Ne-Extraordinary problem 。 Geoch. Cosmochim. Acta V36, 347(1972)
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Presolar grains separated from meteorite SEM-Secondary electron image S. Amari, ApJ690:1424–1431, 2009
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22 Na production somewhere The relatively short half-life and the 1.275 MeV -ray make the 22 Na a possibly sensitive probe for the diagnosis of nearby Nova outbursts from the Sun.
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International Gamma-Ray Astrophysics Laboratory European Space Agency http:// www.esa.int/science/integral
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Milky Way seen by 26 Al -ray at satellite observatory INTEGRAL observatory total of about 2.8 solar masses of 26 Al in our galaxy
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22 Na -ray observation 22 Na: only an upper limit of 3.7 10 -8 M ⊙ of ejected 22 Na by any nova in the Galactic disk. COMPTEL aboard CGRO observed five nearby Ne-type novae What happened to the 22 Na?
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Classic Nova Thermonuclear outburst takes place on the surface of a white dwarf component in a close binary system José et al., APJ, 520:347-360(1999)
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Main nuclear paths in the synthesis of 22 Na Four reactions that control the synthesis of 22 Na: 20 Ne(p, ) 21 Na 21 Ne(p, ) 22 Na 21 Na(p, ) 22 Mg 22 Na(p, ) 23 Mg José et al., APJ, 520:347-360(1999)
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resonance strength (= integrated cross section over resonant region) i values at resonant energies) rate entirely determined by “resonance strength” and energy of the resonance E R experimental info needed partial widths i spin J energy E R Narrow resonances
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CRIB 22 Na+p experiment 22 Na beam production conditions Primary beam 22 Ne 7+ Energy6.1 MeV/A Intensity500 enA Production reaction 22 Ne(p, n) 22 Na Production target 1 H gas, 1.15 mg/cm 2 (LN 2 -cooled, 400 Torr, 90K, 80 mm in length February 28-March 10, 2012
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22 Na RIB production Purity: ~2 × 46.8 % At F3, with 50 kV of Wien Filter
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Gas target Length: 300 mm Windows: 2.5 m Havar (front), 26.5 m Mylar (back). Silicon Telescopes DSSSD+SSD 50 50 mm 2 Experimental setup at F3 chamber 22 Na: 37.1 MeV (in gas) 2.5×10 5 pps (on target)
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Setup for 22 Na+p/ 22 Na PPACGas target H 2 : 310 torr He: 400 torr Ar: 75 torr
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Light recoils from 22 Na+p p d Proton spectrum from 22 Na(p,p) and background
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Excitation function of 22 Na(p,p)
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Multi-level R- matrix analysis
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Paper accepted for publication in PRC
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E c.m. /MeV d /d /mb/sr ST1 ST2 ST3 22 Na+ Excitation Function 激发能区太窄,并且发 现使用气体靶会导致较 大几何不确定性!
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22 Na+p with a solid (CH 2 ) n target 固体靶的优势 反应点的几何不确定性小,因此在低能段更准确。 能够覆盖更宽的 23 Mg 激发能区,同时测量 22 Na(p, ) 23 Mg 和 19 Ne( ,p) 22 Na 感兴趣的 23 Mg 能级。 比气体靶实验更简单易行。
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Motivations of another 22 Na+p measurement To study the relevant resonances in 23 Mg over larger excitation energy region using 22 Na+p channel with a well-developed thick target method To study the 23 Mg energy level related to the 19 Ne( ,p) 22 Na reaction
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X-RAY BURSTERS & X-RAY PULSARS
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RIBLL1 -低能次级束测试 参照东京大学 CRIB 装置,在 RIBLL1 上加装气体靶。 产生反应(逆运动学) 1 H( 22 Ne, 22 Na)n 主束 ( 22 Ne 7+ ) 能量: 6.2 MeV/u ;流强: ~ 300 enA (RIBLL1 入口 ) 气体靶 氢气 [ 30 , 80 毫米长, 500 mbar 大气压,酒精冷却~ 2 C ] 次级束 ( 22 Na 11+ ) 纯度: 30 %,流强: 1.7 10 4 pps 预期: 1000 enA 22 Ne, 1atm 氢气, 22 Na 流强可达 2 10 5 pps
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束流粒子鉴别图 狭缝条件: C1: 15 mm ( E/E= 1.5%), C2: 10 mm ( E/E= 1.0%) TOF1 计数率: 46 万每秒 TOF2 计数率: 7.6 万每秒 T1 - T2 传输效率: 17 % } 【参见: J.J. He et al., NIMA680(2012)43-47 】 RIBLL 的 22 Na 次级束流
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22 Na 次级束 Primary beam 22 Ne 8+ , 8.2 AMeV Intensity500 enA Production reaction 22 Ne(p, n) 22 Na Production target 1 H gas, 0.81 mg/cm 2 (Alcohol-cooled, 1 atm, -30 C, 80 mm in length
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实验设置 22 Na: 93 MeV, E c.m. ≈ 4.0 MeV (CH 2 ) n 靶: 7.5 mg/cm 2
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谢谢大家!
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Beam size on target position by extrapolation
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22 Na(p, ) 23 Mg Reaction Rate
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