Nebraska’s Statewide Outreach and Education Experiment

1. Nebraska’s Statewide Outreach and Education Experiment The Cosmic Ray Observatory Project WashingtonAreaLargeTime-coincidenceArray Needles in a Haystack Neutrinos Among The Cosmic Rays The Henderson Mine Project Tuesday, September 28, 2004 Dan Claes University of Nebraska-Lincoln

2. 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.

3. 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

4. 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

6. 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

7. 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!

9. 1900Charles T. R. Wilson’s ionization chamber • Electroscopes eventually discharge even • when all known causes are removed, • i.e., even when electroscopes are • sealed airtight • flushed with dry, • dust-free filtered air Also necessary to be • far removed from any • radioactive samples But even when • shielded with 2 inches of lead STILL slowly discharges! seemed to indicate an unknown radiation with greater penetrability than x-rays or radioactive rays • Speculating they might be extraterrestrial, Wilson ran • underground tests at night in the Scottish railway, but • observed no change in the discharging rate.

10. Jesuit priest, Father Thomas Wulf , developed an • ionization chamber with a design planned specifically for • high altitude balloon flights. • A taut wire pair replaced the gold leaf. • This basic design became the pocket • dosimeter carried to record one’s • total exposure to ionizing radiation. 0

11. 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

12. 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

13. Before the explosion: Mass, M vo = 0 After the explosion: v1 v2 m2 m1

14. v1 v2 m1 m2 With no external forces, the momentum P must be conserved. Initially:P = 0 Finally: P= m1v1+ m2v2= 0 m1v1 = - m2v2 vo = 0

15. p = 0 pgas procket pi = 0 = pf pgas = – procket = pgas + procket pi = 0 = pf = prifle + pbullet prifle = – pbullet

16. 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

17. ? 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

18. -decay -decay

19. Some Alpha Decay Energies and Half-lives Isotope KEa(MeV) t1/2l(sec-1) 232Th 4.01 1.41010 y 1.610-18 238U 4.19 4.5109 y 4.910-18 230Th 4.69 8.0104y 2.810-13 238Pu 5.50 88years 2.510-10 230U 5.89 20.8 days 3.910-7 220Rn 6.29 56 seconds 1.210-2 222Ac 7.01 5 seconds 0.14 216Rn 8.05 45.0msec 1.5104 212Po 8.78 0.30msec 2.3106 216Rn 8.78 0.10msec 6.9106

20. 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

21. 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!

22. 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)

23. 1932n  p + e- + neutrino charge0 +1 -1 ? mass939.56563 938.27231 0.51099906? MeV MeV MeV neutrino mass < 5.1 eV < me /100000  0

24. 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

25. 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 of 51013 neutrinos/cm2-sec observed 2-3 p + neutrino events/hour

26. UndergroundNeutrinoObservatory The proposed next-generation underground water Čerenkov detector to probe physics beyond the sensitivity of the highly successful Super-Kamiokande detector in Japan

27. 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.

28. 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

29. 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.

30. SALTA: Snowmass Area Large Time-Coincidence Array Empire • Aspen High School, Aspen, CO • Basalt High School, Basalt, CO • Roaring Fork Valley High School, • Carbondale, CO • Lake County High School, • Leadville, CO • The highest-elevation school in U.S. • -- 10,152 feet above sea level • Clear Creek High School, • Empire, CO

31. SALTA Workshop, July 2001, Snowmass, CO Making detectors light-tight Polishing scintillator edges outside Conference Center mass phototube gluing

32. CROP article in Lincoln Journal Star, 7 August 2003

33. The Chicago Air Shower Array CROPrecycles retired detectors from theChicago Air Shower Array • Located in the Utah Desert • 1089 stations, 15m spacing • covering 0.23 square km each houses 4 scintillators w/tubes 1 high and 1 low voltage supply

34. The CROP team at Chicago Air Shower Array (CASA) site September 30, 1999 U.S. Army Photo

35. 2000 scintillator panels, 2000 PMTs, 500 low and power supplies at UNL CASA detectors’ new home at the University of Nebraska

36. Read out by 10 stage EMI 9256 photomultiplier tube 2 ft x 2 ft x ½ inch PMMA (polymethyl methacrylate) doped with a scintillating fluor Recycling material inherited from The Chicago Air Shower Array

37. 1 Leadville 10 miles

38. Henderson Mine Visit Dec 4, 2003 hosted by Chip deWolfe Marc WhitleyDiana KruisNancy Spletzer Aspen High SchoolBasalt High SchoolClear Creek High School Michelle Ernzen Laura French Lake County School Roaring Fork Valley Hans-Gerd Berns University of Washington Dan Claes University of Nebraska

39. Scouted 3 possible locations between 2800-3900 ft depths 110 power available

40. January 13-15 – SALTA students checked out condition of their detectors

41. Aspen Center for Physics July, 2004: Back for MORE!

42. Aspen Center for Physics Education & Outreach Workshop July 6-8 SALTA schools take over the library, setting up cosmic ray telescopes, for training in the new DAQcard that will facilitate all their data-taking.

43. Detector Configuration Two modules each a pair of telescoped of detectors • requiring a coincidence in each pair helps cut down “noise” • sandwiched with lead sheet ¼ in lead

44. At mining level (3000 mwe) any one (2 ft  2 ft) panel • can be expected to count only a handful of events / day • May need week(s) long runs We will move detectors at 2-3 week intervals

45. Desktop Base Station An ~identical pair of modules will run in a fixed location (surface office) to establish a baseline