Title: Eliminating Nuclear Bombs with Ultra-High Energy Neutrinos
1Eliminating Nuclear Bombs with Ultra-High Energy
Neutrinos
- Hiroyuki Hagura (KEK)
- Hirotaka Sugawara (Univ. of Hawaii)
- Toshiya Sanami (KEK)
2Outline
- Introduction
- Mean free paths of neutrinos
- What is a nuclear weapon?
- How to eliminate the nuclear weapons from
the other side of the Earth? - Muon accelerator design
- Conclusions
- Discussion
3Introduction
- Non-proliferation of nuclear weapons is difficult
at present in spite of the existence of NPT. - Detecting nuclear bombs globally and eliminating
them safely are very important for global
security. - Interestingly enough, neutrino is considered to
be the only particle that is capable of doing
that on the global scale. - Big collaboration of particle, nuclear, reactor
and accelerator physicists and security experts
will play an essential role for the purpose.
4Cross-sections for neutrino-nucleus scattering
process
Consider a neutrino of energy E scattering off
a target nucleus X of proton number Z and
neutron number N
n
5Mean free paths of neutrinos
- Calculated at the tree level
- Only two flavors (u and d quarks) are included
- Scaling functions with no QCD corrections
- No neutrino oscillation is assumed
- Protons and neutrons are uniformly distributed
inside the Earth - If one includes several effects, the
cross-sections will become a few times larger,
leading to smaller mean free paths
6What is a nuclear weapon?
- Ignition by explosives
- Shock wave is created, density wave makes Pu
and U go beyond the critical point - Initiator gets broken (aluminum foil)
- In 10 sec super-critical fission reaction
occurs everywhere in the core - Tamper works to suppress fizzle explosion
- Full explosion produces a bomb yield of 20 kt
explosive A
239
238
U tamper
238
initiator
-6
Pu core
239
ignition system
explosive B
7How to eliminate them from the other side of the
Earth?
- Hadron shower hits the target bomb and causes
sub-critical nuclear fissions - The temperature of the bomb increases
- Above 250 degrees the surrounding explosives
(dynamite) get ignited - The rest of the process is the same as the
ordinary nuclear bomb explosion
E 100 1000 TeV Mean free path
diameter of the Earth
n
nuclear bomb
Muon accelerator
neutrino beam
hadron shower
inside of the Earth
8The important difference!
- The bomb is exposed to hadron beams which play
the role of initiator. - The beams cause sub-critical chain reactions to
start before the shock wave reaches the center - Such a phenomenon is well known as the fizzle
explosion - This makes the destruction of the nuclear bomb
relatively safe.
shock wave
hadron shower
Pu core
initiator
shock wave
9What are the required parameters?
- 10 fissions per 10 kg of Pu to reach 300
degrees. - 10 fissions per 10 kg of Pu to vaporize all
the plutonium. This is needed when the plutonium
is stored away from the explosive material.
16
239
239
19
We can calculate numerically how many neutrinos
are needed to reach this value in a given time.
10Numerical results tentative
Using three MC programs, that is, HERWIG6, MARS
and MCNPX, we have obtained
- For E 1000 TeV neutrinos, the required
number of neutrinos is 10 in a few seconds. - For lower-energy neutrinos, we will need more
larger intensity.
n
14
11Muon accelerator design
- Two synchrotrons A and B, which are 100km in
radius and revolvable, encircle a large
mountain. - Muons emit neutrino beams along the straight
sections P P and Q Q , aiming at target
bomb(s) placed on the opposite side of the
Earth. - However, large synchrotron radiation takes place,
which is very difficult to overcome.
hazardous plane 2
synchrotron B
-
m
m
hazardous plane 1
synchrotron A
2
1
2
1
injection system
neutrino radiation hot spot
12Is it practical to do so?
Number of questions
- Can we steer the beam?
- Dq 10 (rad)
- -- Not easy but possible
- Current achievement Dq 10 (rad)
- Can we make 10 neutrinos in a short period, for
example, in 1 sec? - -- High-intensity proton machine (now 10
/sec) - Can we make a 1 PeV machine?
- -- The hardest problem (now 1-10 TeV)
-7
-6
14
13
13Conclusions
- UHN neutrinos can be very useful
- Global disarmament
- Earth tomography (X-ray by neutrino)
- Perhaps communication (a prototype of SETI)
- Technology development
- Invention of much stronger magnet 10Tesla
- High-energy, high-intensity accelerator
- Fine alignment
- Detectability of nuclear bombs (J. Learned)
- Financial support
- Massive investment (50B) will be needed
- World-wide collaboration
14Discussion
- More precise calculations of the cross-sections
for neutrino-nucleus scattering - More information on the structure functions of
Pu/U - Further numerical studies (now in progress)
- Determination of the precise value of the beam
energy and intensity required for
destruction/detection - Effect of UHE neutrinos on nuclear reactors in
operation - Another design of the 1 PeV muon accelerator
- Linac more practical? (J. Learned, B. J. King)
- Other methods of producing UHE neutrinos
- Constructing a huge accelerator on the Moon (J.
Learned) - Practical method of detecting nuclear bombs
- Anti-neutrino detector will be used for the
detection