Messages From Deep Space Deep Underground The Henderson Mine Project Thursday, December 15, 2005 Dan Claes University of Nebraska-Lincoln
Henri Becquerel(1852-1908) received the 1903 Nobel Prize in Physics for the discovery of natural radioactivity. Wrapped photographic plate showed clear silhouettes, when developed, of the uranium salt samples stored atop it. • 1896 While studying the photographic images of various fluorescent & phosphorescent • materials, Becquerel finds potassium-uranyl sulfate spontaneously emits radiation • capable of penetrating thick opaque black paper • aluminum plates • copper plates • Exhibited by all known compounds of uranium (phosphorescent or not) • and metallic uranium itself.
In ordinary photographic applications light produces • spots of submicroscopic silver grains • a fast charged particle can leave a trail of individual Aggrains • 1/1000 mm (1/25000 in) diameter grains • plates coated with thick emulsions (gelatins carrying silver • bromide crystals) clearly trace the tracks of charged particles
1898Marie Curie discovers thorium (90Th) Together Pierre and Marie Curie discover polonium (84Po) and radium (88Ra) 1899Ernest Rutherfordidentifies 2 distinct kinds of rays emitted by uranium - highly ionizing, but completely absorbed by 0.006 cmaluminum foil or a few cm of air - less ionizing, but penetrate many meters of air or up to a cm of aluminum. 1900P. Villard finds in addition to rays, radium emits - the least ionizing, but capable of penetrating many cm of lead, several feet of concrete
a g B-field points into page b 1900-01 Studying the deflection of these rays in magnetic fields, Becquerel and the Curies establish rays to be charged particles
1900-01 Using the procedure developed by J.J. Thomson in 1887 Becquerel determined the ratio of charge q to mass m for : q/m = 1.76×1011 coulombs/kilogram identical to the electron! : q/m = 4.8×107 coulombs/kilogram 4000 times smaller!
1911-12 • Austrian physicist Victor Hess, of the • Vienna University, and 2 assistants, • carried Wulf ionization chambers up in • a series of hydrogen balloon flights. • taking ~hour long readings at several • altitudes • both ascending and descending • radiation more intense above • 150 meters than at sea level • intensity doubled between • 1000 m to 4000 m • increased continuously through • 5000 meters Dubbed this “high” level radiation Höhenstrahlung Hess lands following a historic 5,300 meter flight. August 7, 1912 National Geographic photograph
1937 Marietta Blau and Herta Wambacher report “stars” of tracks resulting from cosmic ray collisions with nuclei within the emulsion Cosmic ray strikes a nucleus within a layer of photographic emulsion 50mm
primary proton 1936 Millikan’s group shows at earth’s surface cosmic ray showers are dominated by electrons, gammas, and X-particles capable of penetrating deep underground (to lake bottom and deep tunnel experiments) and yielding isolated single cloud chamber tracks
The Cosmic Ray Energy Spectrum Cosmic Ray Flux (1 particle per m2-sec) (1 particle per m2-year) (1 particle per km2-year) Energy (eV)
Two possible sources of the highest energy cosmic rays Colliding galaxies Active galactic nucleus
Before the explosion: Mass, M vo = 0 After the explosion: m1 m2 v1 v2 p = 0 pgas procket pi = 0 = pf pgas = – procket = pgas + procket
A cannon rests on a railroad flatcar with a total mass of 1000 kg. When a 10 kg cannon ball is fired at a speed of 50 m/sec, as shown, what is the speed of the flatcar? A) 0 m/s B) ½ m/s to the right C) 1 m/s to the left D) 20 m/s to the right
For these two vehicles to be stopped dead in their tracks by a collision at this intersection A) They must have equal mass B) They must have equal speed C) both A snd B D) is IMPOSSIBLE
Car A has a 650 kg mass and is traveling east at 10 m/sec. Car B has a 500 kg mass and is traveling north 20 m/sec. The two cars collide, and lock bumpers. Neglecting friction which arrow best represents the direction the combined wreck travels? A B C 650 kg 10 m/sec 500 kg 20 m/sec
? A bomb at rest explodes into four fragments. The momentum vectors for three of the fragments are shown. Which arrow below best represents the momentum vector of the fourth fragment? C D A B
? C D A B
-decay E = mc2 -decay
Some Alpha Decay Energies and Half-lives Isotope KEa(MeV) t1/2l(sec-1) 232Th 4.01 1.41010 y 1.610-18 238U 4.19 4.5109 y 4.910-18 230Th 4.69 8.0104y 2.810-13 238Pu 5.50 88years 2.510-10 230U 5.89 20.8 days 3.910-7 220Rn 6.29 56 seconds 1.210-2 222Ac 7.01 5 seconds 0.14 216Rn 8.05 45.0msec 1.5104 212Po 8.78 0.30msec 2.3106 216Rn 8.78 0.10msec 6.9106
1930 Series of studiesofnuclear beta decay, e.g., Potassiumgoestocalcium19K40 20Ca40 Coppergoestozinc29Cu64 30Zn64 Borongoestocarbon5B12 6C12 Tritiumgoes tohelium1H3 2He3 Potassium nucleus Before decay: After decay: A B
1932 Once the neutron was discovered, included the more fundamental n p + e For simple 2-bodydecay, conservation of energy and momentum demand both the recoil of the nucleus and energy of the emitted electron be fixed (by the energy released through the loss of mass) to a single precise value. Ee = (mA2 - mB2 + me2)c2/2mA but this only seems to match the maximum value observed on a spectrum of beta ray energies!
No. of counts per unit energy range 0 5 10 15 20 Electron kinetic energy in KeV The beta decay spectrum of tritium ( H He). Source: G.M.Lewis, Neutrinos (London: Wykeham, 1970), p.30)
Energy spectrum of beta decay electrons from 210Bi Intensity Kinetic energy, MeV
-decay spectrum for neutrons ? Electron kinetic energy in MeV
1932n p + e- + charge0 +1 -1 ? mass939.56563 938.27231 0.51099906 MeVMeVMeV neutrino ??? 0 ? <0.78232 MeV spin ? ½ ½ ½ ½ the Fermi-Kurie plot. The Fermi-Kurie plot looks for any gap between the observed spectrum and the calculated Tmax neutrino mass < 5.1 eV < me /100000 0
Niels Bohr hypothesized some new quantum mechanical restriction on the principle of energy conservation, but Pauli couldn’t buy that: Wolfgang Pauli 1900-1958
Dear Radioactive Ladies and Gentlemen, as the bearer of these lines, to whom I graciously ask you to listen, will explain to you in more detail, how because of the "wrong" statistics of the N and Li6 nuclei and the continuous beta spectrum, I have hit upon a desperate remedy to save the "exchange theorem" of statistics and the law of conservation of energy. Namely, the possibility that there could exist in the nuclei electrically neutral particles, that I wish to call neutrons, which have spin 1/2 and obey the exclusion principle and which further differ from light quanta in that they do not travel with the velocity of light. The mass of the neutrons should be of the same order of magnitude as the electron mass and in any event not larger than 0.01 proton masses. The continuous beta spectrum would then become understandable by the assumption that in beta decay a neutron is emitted in addition to the electron such that the sum of the energies of the neutron and the electron is constant... I agree that my remedy could seem incredible because one should have seen those neutrons much earlier if they really exist. But only the one who dare can win and the difficult situation, due to the continuous structure of the beta spectrum, is lighted by a remark of my honoured predecessor, Mr Debye, who told me recently in Bruxelles: "Oh, It's well better not to think to this at all, like new taxes". From now on, every solution to the issue must be discussed. Thus, dear radioactive people, look and judge. Unfortunately, I cannot appear in Tubingen personally since I am indispensable here in Zurich because of a ball on the night of 6/7 December. With my best regards to you, and also to Mr Back. Your humble servant . W. Pauli, December 1930
"I have done a terrible thing. I have postulated a particle that cannot be detected."
1953, 1956, 1959 Savannah River (1000-MWatt) Nuclear Reactor in South Carolina looked for the inverse of the process: n p + e- + neutrino p + neutrino n + e+ Cowan & Reines with estimate flux of51013 neutrinos/cm2-sec observed 2-3 p + neutrino events/hour We have never observed What does that tell us? n+ neutrino p + e-
The Nuclear pp cycle producing energy in the sun 6 protons 4He + 6g+ 2e + 2p 26.7 MeV Begins with the reaction 0.26 MeV neutrinos
Under the influence of a magnetic field m+ p+ m+ energy always predictably fixed by Ep simple 2-body decay! p+m+ + neutrino? charge +1 +1 ? spin 0½? 0 ½
n p + e- + neutrino? p+m+ + neutrino? Then m-e- + neutrino? p ??? m e As in the case of decaying radioactive isotopes, the electrons’s energy varied, with a maximum cutoff (whose value was the 2-body prediction) 3bodydecay! e m 2 neutrinos
1962Lederman,Schwartz,Steinberger Brookhaven National Laboratory using aas a source ofantineutrinos and a 44-footthick stack of steel (from a dismantled warship hull) to shield everything but the ’s found 29 instances of + p + + n but none of + p e+ + n
Homestake Mine Experiment • 1967 • built at Brookhaven labs • 615 tons of tetrachloroethylene • Neutrino interaction 37Cl37Ar • (radioactive isotope, ½ = 35 days) • Chemically extracting the 37Ar, • its radioactivity gives the number • of neutrino interactions in the vat • (thus the solar neutrino flux). • Results: Collected data 1969-1993 • (24 years!!) • gives a mean of 2.5±0.2 SNU • while theory predicts 8 SNU • (1 SNU = 1 neutrino interaction • per second for 10E+36 target atoms). • This is a neutrino deficit of 69%.
Solar models predict the spectrum and flux of solar neutrinos reaching the earth The energy spectrum of solar neutrinos predicted by the BP04 solar model. For continuum sources, the neutrino fluxes are given in number of neutrinos cm-2s-1 MeV-1 at the Earth's surface. For line sources, the units are number of neutrinos cm-2s-1. Total theoretical uncertainties are shown for each source. The difficult-to-detect CNO neutrino fluxes have been omitted in this plot.
The Solar Neutrino Problem The rate of detection of solar e’s from is 3 smaller than expected!
Is the sun’s core cooler than we thought? 6% Is it a different age than we had assumed? 1998 New and extraordinarily precise measurements of “solar sound speeds” • small oscillations in spectral line strengths • studied by solar seismologists • due to pressure waves traversing the solar volume confirm the predictions of internal temperature and pressure by standard solar models to with 0.1%
Atmospheric Neutrino Detection Each pion decays by → + all showers start with s and Kaons (all Ks decaying rapidly into s) and each muon decays by → e + e + e Note: at sea level e N Ne 2 = e e e e
Given the time dilation of muon lifetimes (and the probabilistic nature of their decays) we can still calculate/simulate the ratio we expect to observe at the ground, and compare: One detector measures this significantly more accurately than any other SuperKamiokande They find Rsub-GeV =0.63 0.06 Rmulti-GeV =0.65 0.09
“Evidence for an oscillatory signature in atmospheric neutrino oscillation” Y. Ashie, et. al. (the Super-Kamiokande Collaboration) Phys. Rev. Lett. 93, 101801 (2004).
UndergroundNeutrinoObservatory The proposed next-generation underground water Čerenkov detector to probe physics beyond the sensitivity of the highly successful Super-Kamiokande detector in Japan
The SuperK detector is a water Čerenkov detector 40 m tall 40 m diameter stainless steel cylinder containing 50,000 metric tons of ultra pure water The detector is located 1 kilometer below Mt. Ikenoyama inside the Kamioka zinc mine.
The main sensitive region is 36 m high, 34 m in dia viewed by 11,146 inward facing Hamamatsu photomultiplier tubes surrounding 32.5 ktons of water
UndergroundNeutrinoObservatory • 650 kilotons • active volume: • 440 kilotons • 20 times larger • than • Super-Kamiokande $500M The optimal detector depth to perform the full proposed scientific program of UNO 4000 meters-water-equivalent or deeper major components: photomultiplier tubes, excavation, water purification system.
DUSEL: A National Science Foundation initiative to establish a national underground laboratory for research in physics, Earth and environmental sciences, civil and Mining engineering, and the Biosciences. Soudan Mine Soudan, MN Icicle Creek Cascades, WA Homestake Mine Lead, SD Mount San Jacinto, CA Henderson Mine Empire, CO Kimballton Mine Giles Co.,West VA WIPP Carlsbad, NM “The science cuts across disciplinesand Directorates (ENG, GEO, and MPS) and provides opportunities for transformational breakthroughsand to educate the scientists & engineers of the 21stcentury” Michael S. Turner, Assistant Director for Mathematics and Physical Science Division (NSF)
Geo-outposts will explore below the ore body! Lt Blueproposed access ramps Green exploratory drill holes Dk Blue – Geo research areas Red – Added geo access • Ore Geology, Magmatic- Hydrothermal Processes, and Petrogeneis • Hydrogeology • Coupled Processes • Geophysics • Geophysical imaging • Stress in the earth