RIBLL中的飞行时间探测器的性能研究
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摘要
在RIBLL所有的离子鉴别探测器中,飞行时间探测器对于鉴别和分离RIB起着至关重要的作用。因此,很有必要对飞行时间探测器的性能进行研究,以便找出提高探测器性能的合理方案。本文的主要内容就是对RIBLL中飞行时间探测器的性能进行模拟研究。
在本工作中,我们利用GEANT4这一蒙特卡洛模拟软件,首先构造了和实验一致的飞行时间探测器装置,定义了粒子源和相应的物理过程。在物理过程中,入射粒子与闪烁体之间主要是低能电磁相互作用过程,还涉及到光子吸收过程、边界过程和光子的传输过程。
其次,对该探测器的性能做了比较深入细致的模拟研究。研究结果表明,光子总的收集效率与粒子在闪烁体上的入射位置有关；时间分辨与入射粒子的入射位置、种类、能量以及铝反射层的反射率有关。选用了入射束斑均相同的不同的重离子作离子源,并分别进行了模拟实验,得到了各自的时间分辨。粒子的入射位置在闪烁体的中心位置附近时,光子总的收集效率较好；入射点在中心稍微靠下的位置时探测器的时间分辨最好；铝反射面的反射系数较低时,经过一次反射到达光阴极的光子数目较多,但经二次反射到达光阴极的光子数目较少,时间分辨较好；入射粒子的能量对时间分辨的影响比较大,随着能量的增大时间分辨逐渐变差。
最后,通过进一步地分析和讨论,并结合本模拟实验的研究结果对飞行时间探测器提出了一些建议和改进方案。
Time of flight detector plays an essential role for the identification and isolation of radioactive ion beam in all the particle identification detectors in RIBLL. Hence, it is necessary to study the TOF detector performance so as to find a reasonable solution to improve it. In this paper, the performance of TOF in RIBLL was simulated and then studied.
Firstly, we constructed TOF detector consistently with experimental set up using Monte Carlo Kit GEANT4, defined the ion source and all the corresponding physical process. Of all the physical process, low energy electromagnetic processes is the main interaction between incident particle and scintillator, while photon absorption process,boundary process and photon transmission are also involved.
Secondly, the detector performance is studied intensively. The results show that total photon collection efficiency is associated with the particle incident location on scintillator, time resolution is related to the kinds of incident particle, incident position, energy and reflectivity of Aluminum reflector. Different heavy ions were selected with same size of beam spots, and simulated, then time resolutions was achieved respectively. The total photon collection efficiency is best when incident particle location is of the center of scintillator. When the incident point is a litter lower to the center, the time resolution is best. If Aluminum reflectance is smaller, the number of photons with only one reflection arriving at the photocathode will be larger, the number of photons with 2 reflections will be smaller, which causes a better time resolution. The energy of the incident particle influence the time resolution greatly. The time resolution became worse following the increase of incident energy.
Finally, combining the results of the simulation and further analysis, discussion, we put forward some suggestions and improvements to the TOF detector.
在本工作中,我们利用GEANT4这一蒙特卡洛模拟软件,首先构造了和实验一致的飞行时间探测器装置,定义了粒子源和相应的物理过程。在物理过程中,入射粒子与闪烁体之间主要是低能电磁相互作用过程,还涉及到光子吸收过程、边界过程和光子的传输过程。
其次,对该探测器的性能做了比较深入细致的模拟研究。研究结果表明,光子总的收集效率与粒子在闪烁体上的入射位置有关；时间分辨与入射粒子的入射位置、种类、能量以及铝反射层的反射率有关。选用了入射束斑均相同的不同的重离子作离子源,并分别进行了模拟实验,得到了各自的时间分辨。粒子的入射位置在闪烁体的中心位置附近时,光子总的收集效率较好；入射点在中心稍微靠下的位置时探测器的时间分辨最好；铝反射面的反射系数较低时,经过一次反射到达光阴极的光子数目较多,但经二次反射到达光阴极的光子数目较少,时间分辨较好；入射粒子的能量对时间分辨的影响比较大,随着能量的增大时间分辨逐渐变差。
最后,通过进一步地分析和讨论,并结合本模拟实验的研究结果对飞行时间探测器提出了一些建议和改进方案。
Time of flight detector plays an essential role for the identification and isolation of radioactive ion beam in all the particle identification detectors in RIBLL. Hence, it is necessary to study the TOF detector performance so as to find a reasonable solution to improve it. In this paper, the performance of TOF in RIBLL was simulated and then studied.
Firstly, we constructed TOF detector consistently with experimental set up using Monte Carlo Kit GEANT4, defined the ion source and all the corresponding physical process. Of all the physical process, low energy electromagnetic processes is the main interaction between incident particle and scintillator, while photon absorption process,boundary process and photon transmission are also involved.
Secondly, the detector performance is studied intensively. The results show that total photon collection efficiency is associated with the particle incident location on scintillator, time resolution is related to the kinds of incident particle, incident position, energy and reflectivity of Aluminum reflector. Different heavy ions were selected with same size of beam spots, and simulated, then time resolutions was achieved respectively. The total photon collection efficiency is best when incident particle location is of the center of scintillator. When the incident point is a litter lower to the center, the time resolution is best. If Aluminum reflectance is smaller, the number of photons with only one reflection arriving at the photocathode will be larger, the number of photons with 2 reflections will be smaller, which causes a better time resolution. The energy of the incident particle influence the time resolution greatly. The time resolution became worse following the increase of incident energy.
Finally, combining the results of the simulation and further analysis, discussion, we put forward some suggestions and improvements to the TOF detector.
引文
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[3]Sakurai H, Aoi N, Beaumel D, et al. Search for new neutron rich nuclei with a 70AMeV 48Ca Beam [J]. NuclPhys,1997, A616:311c-315c.
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[14]A. Akindinov, G. Bondarenko, V. Golovin, et al. Nucl Instr & Meth,2005, A539:172.
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[18]Geissel H, Guttner K, Knapp G, et al.. Discrimination between different ions using thin scintillator films as time-of-flight detectors [J]. Nucl Inst and Meth,1978,154:239-243.
[19]Carlson R F, Cox A J, Nasr T N, et al.. Measurements of proton total reaction cross sections for 6Li,7Li,14N,20Ne and 40Ar between 23 and 49 MeV [J]. Nucl Phys,1985, A445:57-69.
[20]R. Bellwied, M. J. Bennett, V. Bernardo, et al. Nucl Instr & Meth,2002, A485:371.
[21]李加兴,詹文龙,郭忠言等.RIBLL中的TOF测量[J].高能物理与核物理,1999,23(3)：231-236.
[22]P. Bogorad, E. J Brash, G. D. Cates, et al. Nucl Instr & Meth,1997, A398:211.
[23]B. V. Dinesh, R. G. Thomas, B. K. Nayak, et al. Nucl Instr & Meth,2000, A452:338.
[24]Clive Field,Gholam Mazaheri,Emlyn W. Hughes,G Mark Jones.Nucl Instr&Meth,2004,A531：569.
[25]R. A. Lewis, C. J. Hall, B. parker, et al. Nucl Instr & Meth,1997, A392:42.
[26]Y. L. Ye, Z. Y. Di, Z. H. Li, et al. Nucl Instr & Meth,2003, A515:718.
[27]詹文龙,郭忠言等.兰州放射性束流线[J].中国科学(A辑),1999,29(1)：77-84.
[28]E. Ceron Zeballos, I. Crotty, D. Hatzifotiadou, et al. Nucl Instr & Meth,1997, A392:150
[29]M. Abbrescia, E. Bisceglie, G. Iaselli, et al. Nucl Instr & Meth,1997, A394:341.
[30]CERN2LHCExperiments Committee.CMS Technical Design Report 3,The Muon Project,Dec. 1997
[31]N. Ghodbane. Nucl Phys,2003, B125:258.
[32]J. Kaminski, M. Ball, F. Bieser, et al. Nucl Instr & Meth,2004, A535:201.
[33]T. Kii, T. Shima, T. Baba, Y. Nagai. Nucl Instr & Meth,2005, A522:329.
[34]陈朝清.核技术.1986,第5期：19.
[35]李加兴,詹文龙,郭忠言等.RIBLL中粒子鉴别探测器[J].核技术,2001,24(4)：309-316.
[36]Zhao Youxiong, Zhan Wenlong, Guo Zhongyan,et al. Nucl. Instr. Meth.,1995, A355:464-468.
[37]A. Ereditato, K. Niwa, P. Strolin. Nucl Phys,1998, B66:423.
[38]N. D'Ambrosio, Nucl Instr & Meth,2004, A525:193.
[39]K. Kuge, S. Iwakiri, Y. Endo, et al. Radiation Measurements,2007,42:1335.
[40]S. Miyamoto, A. Ariga, T. Fukuda, et al. Nucl Instr & Meth,2007, A575:466.
[41]原子核物理实验方法。复旦大学、北京大学、清华大学合编,1997年.
[42]唐孝威主编.粒子物理实验方法[M].第一版.北京：1982,27-205.
[43]谢一冈,陈昌,王曼等.粒子探测器与数据获取[M].第一版.北京：2003,55-358.
[44]江月松,阎平,刘振玉.光电技术与实验[M].北京：北京理工大学出版社,2000：70-88.
[45]彭其先,马如超,李泽仁,等.光电倍增管脉冲性能研究[J].光子学报,2002,31(5)：618-622.
[46]郭从良,孙金军,方容川,等.光电倍增管的噪声分析和建模[J].光学技术,2003,29(5)：636.
[47]周荣嵋.光电倍增管展望[J].光电子技术,2000,20(2)：84-89.
[48]丁富荣,班勇,夏宗璜编著.辐射物理[M].第一版.北京：2004,62-95.
[49]光电倍增管R2083性能参数手册,HAMAMASTU.
[50]许淑艳.蒙特卡罗方法在实验核物理中的应用[M].北京：原子能出版社,2006.1-27.
[51]裴鹿成,张孝泽.蒙特卡罗方法及其在粒子输运问题中的应用[M].北京：科学出版社,1980,1-20.
[52]Agostinellis,Allison J,Amako K,et al.Geant4A simulation toolkit[J]. Nucl.Instrum.Methods, 2003, A506:250-303.
[53]叶沿林,应军,陈陶.原子核物理评论,1997,14(02)：125-129.
[54]Geant4 User's Guides for Application Developers,2007, http://geant4.web.cern..ch/geant4.
[55]蒋林立.BESⅢ飞行时间计数器的束流实验模拟及离线软件发展研究.中国科学技术大学博士学位论文,2006：61-62.
[2]GuillemaudMueller D, Jacmart J C, Kashy E, et al. Particles stability of the isotopes 26O and 32Neinthere action 44MeV/nucleon 48Ca+Ta [J]. PhysRev,1990, C41:937-941.
[3]Sakurai H, Aoi N, Beaumel D, et al. Search for new neutron rich nuclei with a 70AMeV 48Ca Beam [J]. NuclPhys,1997, A616:311c-315c.
[4]Schneider R, Friese J, Reinhold J,et.al. Production and dentification of 100Sn [J]. ZPhys,1994, A348:241-242.
[5]Lewitowicz M, Anne R, Auger G, et al. Identification of the doubly magic nucleus 100Sninthere action 112Sn+ natNiat 63MeV/nucleon [J]. PhysLett.1994, B332:20-24.
[6]Beamas M, Armbruster P, Czajkowski S, et al. Identification of more than a 100 new isotopes from 238U projectile fission and beam of neutron rich nuclei at BRENDA [J]. NuclPhys,1997, A616:352c-362c.
[7]肖国青,李振中等.兰州重离子研究装置[J].大科学工程装置,2009,24(1)：97-101.
[8]Sherrill B M, Morrissey D J, Nolen J A, et al. The A1200 Projectile Fragment Separator [J]. Nucl. Instr. Meth.,1991, B56/57:1106-1110.
[9]Anne R, Bazin D, Mueller A C, et al. The Achromatic Spectrometer LISE at FANIL [J].Nucl. Instr. Meth.,1987, A257:215-232.
[10]Gessel H, Armbruster P, Behr K H, et al. The GSI Projectile Fragment Separator(FRS):A versatile magnetic system for relativistic heavy ions [J].Nucl. Instr. Meth.,1992, B70:286-297.
[11]Kubo T, Ishihara T M, Inahe N, et al. The RIKEN Radioative Beam Facility.Nucl [J]. Instr. Meth.,1992,B70:309-319.
[12]詹文龙,郭忠言.兰州放射性束流线[J].原子核物理评论,1999,16(4)：218-223.
[13]D. A. Bukin, V. P. Druzhinin, V. B. Golubev, S. I. Serednyakov, Nucl Instr & Meth,1997, A384:360.
[14]A. Akindinov, G. Bondarenko, V. Golovin, et al. Nucl Instr & Meth,2005, A539:172.
[15]Tanihata I, Hamagaki H, Hashimoto O, et al. Measurements of Interaction Cross Section and Nuclei Radii in the Light p-shell Region [J].Phys Rev Lett,1985,55:2676-2679.
[16]赵有雄,詹文龙,郭忠言等.椭球面聚焦型镜像塑料闪烁探测器及其应用[J].核电子学与探测技术1995,15(5)：270-274.
[17]Muga M L, Bumsed D J, Steeger W E, et al. A new time-of-flight particle detector [J]. Nucl Inst and Meth,1970,83:135.
[18]Geissel H, Guttner K, Knapp G, et al.. Discrimination between different ions using thin scintillator films as time-of-flight detectors [J]. Nucl Inst and Meth,1978,154:239-243.
[19]Carlson R F, Cox A J, Nasr T N, et al.. Measurements of proton total reaction cross sections for 6Li,7Li,14N,20Ne and 40Ar between 23 and 49 MeV [J]. Nucl Phys,1985, A445:57-69.
[20]R. Bellwied, M. J. Bennett, V. Bernardo, et al. Nucl Instr & Meth,2002, A485:371.
[21]李加兴,詹文龙,郭忠言等.RIBLL中的TOF测量[J].高能物理与核物理,1999,23(3)：231-236.
[22]P. Bogorad, E. J Brash, G. D. Cates, et al. Nucl Instr & Meth,1997, A398:211.
[23]B. V. Dinesh, R. G. Thomas, B. K. Nayak, et al. Nucl Instr & Meth,2000, A452:338.
[24]Clive Field,Gholam Mazaheri,Emlyn W. Hughes,G Mark Jones.Nucl Instr&Meth,2004,A531：569.
[25]R. A. Lewis, C. J. Hall, B. parker, et al. Nucl Instr & Meth,1997, A392:42.
[26]Y. L. Ye, Z. Y. Di, Z. H. Li, et al. Nucl Instr & Meth,2003, A515:718.
[27]詹文龙,郭忠言等.兰州放射性束流线[J].中国科学(A辑),1999,29(1)：77-84.
[28]E. Ceron Zeballos, I. Crotty, D. Hatzifotiadou, et al. Nucl Instr & Meth,1997, A392:150
[29]M. Abbrescia, E. Bisceglie, G. Iaselli, et al. Nucl Instr & Meth,1997, A394:341.
[30]CERN2LHCExperiments Committee.CMS Technical Design Report 3,The Muon Project,Dec. 1997
[31]N. Ghodbane. Nucl Phys,2003, B125:258.
[32]J. Kaminski, M. Ball, F. Bieser, et al. Nucl Instr & Meth,2004, A535:201.
[33]T. Kii, T. Shima, T. Baba, Y. Nagai. Nucl Instr & Meth,2005, A522:329.
[34]陈朝清.核技术.1986,第5期：19.
[35]李加兴,詹文龙,郭忠言等.RIBLL中粒子鉴别探测器[J].核技术,2001,24(4)：309-316.
[36]Zhao Youxiong, Zhan Wenlong, Guo Zhongyan,et al. Nucl. Instr. Meth.,1995, A355:464-468.
[37]A. Ereditato, K. Niwa, P. Strolin. Nucl Phys,1998, B66:423.
[38]N. D'Ambrosio, Nucl Instr & Meth,2004, A525:193.
[39]K. Kuge, S. Iwakiri, Y. Endo, et al. Radiation Measurements,2007,42:1335.
[40]S. Miyamoto, A. Ariga, T. Fukuda, et al. Nucl Instr & Meth,2007, A575:466.
[41]原子核物理实验方法。复旦大学、北京大学、清华大学合编,1997年.
[42]唐孝威主编.粒子物理实验方法[M].第一版.北京：1982,27-205.
[43]谢一冈,陈昌,王曼等.粒子探测器与数据获取[M].第一版.北京：2003,55-358.
[44]江月松,阎平,刘振玉.光电技术与实验[M].北京：北京理工大学出版社,2000：70-88.
[45]彭其先,马如超,李泽仁,等.光电倍增管脉冲性能研究[J].光子学报,2002,31(5)：618-622.
[46]郭从良,孙金军,方容川,等.光电倍增管的噪声分析和建模[J].光学技术,2003,29(5)：636.
[47]周荣嵋.光电倍增管展望[J].光电子技术,2000,20(2)：84-89.
[48]丁富荣,班勇,夏宗璜编著.辐射物理[M].第一版.北京：2004,62-95.
[49]光电倍增管R2083性能参数手册,HAMAMASTU.
[50]许淑艳.蒙特卡罗方法在实验核物理中的应用[M].北京：原子能出版社,2006.1-27.
[51]裴鹿成,张孝泽.蒙特卡罗方法及其在粒子输运问题中的应用[M].北京：科学出版社,1980,1-20.
[52]Agostinellis,Allison J,Amako K,et al.Geant4A simulation toolkit[J]. Nucl.Instrum.Methods, 2003, A506:250-303.
[53]叶沿林,应军,陈陶.原子核物理评论,1997,14(02)：125-129.
[54]Geant4 User's Guides for Application Developers,2007, http://geant4.web.cern..ch/geant4.
[55]蒋林立.BESⅢ飞行时间计数器的束流实验模拟及离线软件发展研究.中国科学技术大学博士学位论文,2006：61-62.