粒子物理规划及
未来的中微子实验
王贻芳
南昌，2010 高能物理年会
Particle physics: problems and methods
Standard
Model:
Higgs
High energy
accelerators
Beyond
Standard
Model ?
SUSY, Extradimensions.
Compositeness,
…
High intensity
accelerators
Details of SM
(EW & QCD) :
precision test,
Confinement,
Glueballs ?
spectroscopy
of particles…
Underground
experiments
Neutrino
properties:
mass,
oscillation,
magnetic
moment ?
Majorana ?
Cosmology
related problems:
antimatter(CP) ?
Dark matter ?
Relic-neutrinos,
Monopoles ?
Axions ? …
Surface
experiments
Space
experiments
Experiments in the world and at home
High energy
accelerators
High intensity
accelerators
Underground
experiments
Surface
experiments
Space
experiments
Tevetran:
Flavor phys.:
n osc. :
Cosmic-rays
Anti-matter/
dark matter:
D0
CDF
LHC
ATLAS
CMS
ILC
BELLE(II) - b
DAFNE – s
LHCb
PANDA…
High den. phys:
ALICE
J-PARC…
n osc..:
T2K
Minos
Project-X
SuperK
KamLAND…
bb decay:
EXO
Cuore
Gerda…
Dark matter:
HESS
MAGIC
AUGER
CTA
n mass
Katrin
n mag. Mom.
Xmass
Xenon
COUPP…
n Astronomy
Monopole
Proton decay…
Grav. Wave
Relic n
Axions, …
TEXONO
PAMELA
FERMI
AMS…
ATIC
Asrtophysics:
Integral
Hubble
WMAP
Planck…
Participate:
Flavor phys.:
n osc. :
Cosmic-rays
Asrtophysics:
ATLAS, CMS
BESIII - c
Daya Bay
Yang-Ba-Jin
HXMT
高能物理未来发展的基本思路
• High energy accelerators
– 积极参加国际合作
• High intensity accelerators
– 充分利用BESIII，取得国际一流的成果
– 寻机建造下一代加速器
• Underground experiments
– 充分利用大亚湾，取得国际一流的成果
– 准备建造下一代中微子实验
– 寻机建造新的实验：暗物质、bb decay、质子衰变、。。。
• Surface experiments
– 充分利用ASg & ARGO，取得国际一流的成果
– 积极准备建设LHAASO
• Space experiments
– 尽快完成HXMT，取得国际一流的成果
– 寻机建造新的实验：宇宙线、天体物理、暗物质、。。。
时间安排
• 十二五
– 前期建设的丰收期  取得重大国际影响的成果
– 基础能力建设
 达到国际先进水平
– 未来项目的准备与预研  具有国际竞争力
• 十三五 ：重要的建设项目
– 下一代中微子实验：大亚湾二期
– 地下实验：暗物质、bb decay、质子衰变、。。。
– 空间实验：宇宙线、天体物理、暗物质、。。。
• 十四五：重大建设项目
– 下一代加速器
每个新项目必须回答以下问题：
1）为什么（与其它可能的项目比较：科学目标、经费。。。）
2）怎么做（概念设计、国际竞争力、科学意义、经费、技术、进度、风
险。。。）
3）R&D（问题、技术、方案、计划。。。）
5
Neutrino oscillations:
What we know and what we don’t know
• A mixing matrix:
Atmospheric
CP phase & q13
Solar
Majorana phase
• Unknowns in neutrino oscillation:
–
q13 , mass hierarchy, CP phase d + Majorana phase
下一代中微子实验：大亚湾二期
• 中微子振荡：中微子研究的中心
• 中微子振荡三个未解决的问题：
寻找第三种振荡，用q13表示
质量顺序问题
CP对称破缺角
q12太阳中微子振荡
q23大气中微子振荡
n1
n2
n3
 大亚湾中微子实验
大亚湾中微子实验二期
 未来的加速器实验
q13 ?
mi ?
为什么反应堆中微子：
1）加速器中微子实验：造价昂贵 （探测器+加速器）
2）双β实验：造价昂贵，技术困难，风险巨大
3）中微子绝对质量测量：造价昂贵，技术困难
4）反应堆中微子实验：意义重大、风险小、条件优越、造价低、技术可行
测量磁矩：可能的未来，科学风险大
精确测量混合参数：大亚湾、大亚湾二期
Best neutrino source: reactor
• A powerful man-made source
– If not too far, more powerful than solar, atmospheric,
and accelerator neutrinos
• A well understood source（~2%  ~ 0.1%）
– Better than solar(~5-10%), atmospheric(~10%), and
accelerator(~5-10%  2-3% ??) neutrinos
• Adjustable baseline
– Of course, accelerator can do it also
• A free neutrino factory
Neutrino Mass hierarchy
• Mass Hierarchy:
• Fundamental to the Standard Model
• Fundamental to models beyond SM
• Most GUTs predict a normal mass hierarchy  a discriminator of
different GUTs and/or neutrino mass models
• Fundamental to many issues:
– Matter-antimatter asymmetry via leptogenesis in specific seesaw models:
hierarchy related
– Supernova neutrinos: collective flavor transitions due to inverted mass
hierarchy
– Radiative corrections to mn and qij are more sensitive to the inverted
hierarchy
But even more important…
Dirac or Majorana ?
• Neutrino oscillation:
beyond SM in a way of
Dirac or Majorana mode ?
• bb exp. may never give
positive results
• If mass hierarchy is
known, together with next
generation bb exp., the
neutrino Dirac or
Majorana nature can be
determined.
next gen.
bb exp.
Measuring mass hierarchy
• Long baseline accelerator neutrinos
– Through Matter effects
– Expensive, project-X/LBNE in Fermilab/BNL
• Atmospheric neutrinos
– Very weak signal
– Huge detector, Expensive
• Reactor neutrinos
S.T. Petcov et al., PLB533(2002)94
S.Choubey et al., PRD68(2003)113006
– Method: distortion of energy spectrum
– Enhance signature: Transform reactor
neutrino L/E spectrum to frequency regime
using Fourier formalism
• need Sin2(2q13) > 0.02
• Need to know DM223
J. Learned,
PRD 78(2008)071302
Fourier transformation of L/E spectrum
• Frequency regime is in fact the
DM2 regime  enhance the
visible features in DM2 regime
• Take DM2 32 as reference
– NH: DM2 31 > DM2 32 , DM2 31
peak at the right of DM2 32
– IH: DM2 31 < DM2 32 , DM2 31
peak at the left of DM2 32
L/E spectrum
12
Our efforts
• Clear distinctive features:
– FCT:
•
•
NH: peak before valley
IH: valley before peak
– FST:
•
•
NH: prominent peak
IH: prominent valley
• Better than power spectrum
• No pre-condition of Dm223
L. Zhan et al., PRD78:111103,2008
13
Quantify Features of FCT and FST
• To quantify the symmetry
breaking, we define:
RV/LV: amplitude of the right/left valley
in FCT
P/V: amplitude of the peak/valley in FST
• For asymmetric Pee
– NH: RL>0 and PV>0
– IH: RL<0 and PV<0
Two clusters of RL and PV values
show the sensitivity of mass
hierarchy determination
2008-07-17
Baseline: 46-72 km
Sin2(2q13): 0.005-0.05
Others from global fit
L. Zhan et al., PRD78:111103,2008
14
In reality
Unfortunately,
DM221 / DM223 ~ 3%
L. Zhan, et. al., Phys.Rev.D79:073007,2009
Requirement
• To determine mass hierarchy at > 90% CL:
–
–
–
–
Baseline: ~ 58 km, determined by q12
Reactor power > 24 GWth
Flux and detector size: ~ (250-700) ktyear
Ideally, sin22q13 > 0.02 & energy resolution < 2%
• IF sin22q13=0.01, energy resolution < 2% & 700 ktyear
• For sin22q13=0.02 , energy resolution < 3% & 700 ktyear
• Overburden > 1000 MWE
• ~ 60 km from Daya Bay
• A huge ne detector with mass >20kt
– currently the largest on is 1kt (KamLAND & LVD)
Scientific goal: a l0-50kt underground LS
detector 60km from reactor
1. Neutrino Mass hierarchy
2. Precision mixing para. measurement: q12, D M212, DM231 
Unitarity of the mixing matrix
3. Supernova neutrinos ==〉better than SuperK
4. Geo-neutrinos
==〉10 better than KamLAND
5. Atmospheric neutrinos ==〉 SuperK
6. Solar neutrinos ?
7. High energy neutrinos
LVD+MACRO+
1. Point source: GRB, AGN, BH, …
2. Diffused neutrinos
KamLAND+
8. High energy cosmic-muons
SuperK
1.
2.
Point source: GRB, AGN, BH, …
Dark matter
9. Exotics
1.
2.
Sterile neutrinos
Monopoles, Fractional charged particles, ….
Precision measurement of mixing parameter
• Fundamental to the Standard Model and beyond
• Similarities point to a Grand unification of leptons and quarks
• Constrain all PMNS matrix elements to < 1% ! Probing
Unitarity of UPMNS to <1% level !
Current
BESIII
Vub
25%
5%
Vcd
7%
Vcs
Current
Daya Bay II
Dm212
5%
< 1%
1%
Dm223
12%
< 1%
16%
1%
10%
< 1%
Vcb
5%
3%
sin2q12
20%
-
Vtd
36%
5%
Sin2q23

-
Vts
39%
5%
sin2q13
If we can spend (0.1-0.5)B$ for each B/C/superB factories to
understand UCKM (~ 1-2 elements for each factory), why not a superreactor neutrino experiment(~ 3 elements) to understand UPMNS ?
Supernova neutrinos
• Less than 20 events observed so far (2001 Noble prize)
• Assumptions:
–
–
–
–
Distance: 10 kpc (our Galaxy center)
Energy: 31053 erg
Ln the same for all types
Tem. & energy
T(ne) = 3.5 MeV, <E(ne)> = 11 MeV
T(ne) = 5 MeV, <E(ne)> = 16 MeV
T(nx) = 8 MeV, <E(nx)> = 25 MeV
• Many types of events:







ne + p  n + e+, ~ 3000 correlated events
ne + 12C  13B* + e+, ~ 10-100 correlated events
ne + 12C  11N* + e-, ~ 10-100 correlated events
nx + 12C nｘ+ 12C*, ~ 600 correlated events
nx + p  nｘ+ p, single events
ne + e-  ne + e-, single events
nx + e- nｘ+ e-, single events
SuperK can not
see these
correlated events
What to do with Supernova neutrinos
• Energy spectra & fluxes of all types of neutrinos
–
–
–
–
–
–
tem. and average energy of neutrinos
Understand Supernovae
neutrino properties: mass, mixing, …
Earth tomography
Neutrino models
…
• Arrival time of all types of neutrinos  absolute
neutrino mass
Geo-neutrinos
•
•
•
•
•
238U, 232Th
and 40K decays account for 40% of
earth’s power, which is related to
earthquakes, volcanoes, geomagnetism, plate
tectonics, …
They are mainly from mantle and crust, but
not the core
South-china and Japan are different
Geo-neutrinos can tell 238U: 232Th  good
for geo-models
Only way looking inside the earth ?
Already seen by
KamLAND
Geo-neutrinos at Daya Bay II
• A factor of >10 larger than KamLAND
3 years KamLAND
探测器的概念设计
• Neutrino target:
~20kt LS, LAB based
30m(D)30m(H)
• Oil buffer: 6kt
• Water buffer: 10kt
• PMT: 15000 20”
• Cost: ~1.5 B RMB
可能的地点：惠州或海上
据大亚湾/海丰60公里
热功率 > 40 GW
Technical challenges
• Requirements:
– Large detector: >10 kt LS
– Energy resolution: 2%/E  2500 p.e./MeV
Now:
1kt
250 p.e./MeV
• Ongoing R&D:
– Low cost, high QE “PMT”
• A new design exist, patent pending,
• R&D contract to be signed with manufacture
– transparent LS: 15m  >25m
• Find out traces which absorb light, remove it from production
R&D program: ~ 3 years
Useful for many future projects
Support already from IHEP
基于LAB的液体闪烁体研究
南京大学 高能所
测量LAB成分：~4.5% 杂质
利用量子化学的计算，估计、寻找吸收可见光的杂质
初步测量杂质在LAB中的比分
测量LAB样品中的碳、氧、氮、硫等元素及其相关杂质基团
的空间精细结构；运用计算凝聚态物理和计算量子化学的
相关原理与方法，深入解析、研究这些特殊杂质结构组分
的光学性能及其空间组态效应。
Linear- AlkylBenzene (C6H5 -R)
• 研究去除这些杂质的方法
•
•
•
•
26
新型光电倍增管的设计:提高光量子效率
• QE:
– Top: 20%
– Bottom:
• 80%*(20-40)%
– Total:
• (36-52)%
• Collection eff.:
– 60%
• Total: 普通 PMT: 20%*0.6=12%
– (22-31)%
1）采用透射式光电阴极与反射式光电阴极相结合 ==〉
提高光阴极的有效面积 ==〉提高量子效率:
2）采用微通道板作为电子倍增 ==〉
Hammamatzu 的 SBA/UBA
不阻挡光电子 ==〉提高收集效率 光阴极可以得到~40% 光量子
效率; 已基本满足要求
新型光电倍增管的研制
知识产权：已申请全球发明
专利
与国内有关单位合作研制
55所完成的世界第
一个5”MCP-PMT
小结
• BESIII/大亚湾以后的高能物理规划需要大家一起来
讨论
• 中微子物理仍然是一个富矿，值得投入
• 用反应堆中微子测量mass hierarchy值得深入研究：
–
–
–
–
科学目标
探测器设计与优化
选址
关键技术预研
欢迎大家参加，欢迎大家批评指正