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Gd Loading in Water

Gd Loading in Water. Mark Vagins University of California, Irvine. Homestake Detector Meeting @ Fermilab October 12, 2007. Based on work we first did in 2002 here at Fermilab, John Beacom and I wrote the original GADZOOKS! ( G adolinium A ntineutrino D etector Z ealously

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Gd Loading in Water

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  1. Gd Loading in Water Mark Vagins University of California, Irvine Homestake Detector Meeting @ Fermilab October 12, 2007

  2. Based on work we first did in 2002 here at Fermilab, John Beacom and I wrote the original GADZOOKS! (Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super!) paper in late 2003. It was published the following year: [Beacom and Vagins, Phys. Rev. Lett., 93:171101, 2004]

  3. In a nutshell, we proposed a way to tag neutrons produced by the inverse beta process (from supernovae, reactors, etc.) in light water: ne + p e+ + n (l=~4cm, t=~20ms) Much beyond the kiloton scale, you can forget about liquid scintillator, 3He counters, or heavy water! At the 100’s of kton scale and beyond, the only way to see neutrons is a solute mixed into the water... They’re (recently) affordable, have low toxicity and reactivity, and once dissolved are quite transparent. Water soluble GdCl3 or Gd(NO3)3 should do the trick!

  4. All of the events in the present SK low energy analyses are singles in time and space. And this rate is actually very low… just three events per cubic meter per year.

  5. 0.1% Gd gives >90% efficiency for n capture In Super-K this means ~100 tons of water soluble GdCl3 or Gd(NO3)3 Gadolinium has 1500X the n capture cross section of Cl

  6. But, um, didn’t you just say 100 tons?What’s that going to cost? In 1984: $4000/kg -> $400,000,000 In 1993: $485/kg -> $48,500,000 In 1999: $115/kg -> $11,500,000 In 2007: $5/kg -> $500,000

  7. This positron/neutron capture coincidence technique is readily scalable to megaton class detectors at ~1% of their total construction cost, with one important caveat: Hyper-K UNO M3 MEMPHYS In order to be both bigandsensitive, ~40% photocathode coverage (or the equivalent in terms of photon collection) is required in at least part of the detector.

  8. As an example: adding 100 tons of soluble Gd to Super-K would provide at least two brand-new signals: • Precision measurements of the • neutrinos from all of • Japan’s power reactors • (~5,000 events per year) • Will improve world average • precision of Dm212 by 7X 2) Discovery of the diffuse supernova neutrino background [DSNB], also known as the “relic” supernova neutrinos (~5 events per year)

  9. Here’s what the coincident signals in Super-K-III with GdCl3 or Gd(NO3)3 will look like (energy resolution is applied): Most modern DSNB range

  10. In addition to our two guaranteed new signals, it is likely that adding gadolinium to SK-III will provide a variety of other interesting possibilities: • Sensitivity to very late-time black hole formation • Full de-convolution of a galactic supernova’s n signals • Early warning of an approaching SN n burst • (Free) proton decay background reduction • New long-baseline flux normalization for T2K • Matter- vs. antimatter-enhanced atmospheric n samples(?)

  11. How good a job can Super-K do - by itself - on the solar neutrino parameters? = 4.1 live years of data without gadolinium = ~3 years with gadolinium

  12. KamLAND alone SK + SNO + KamLAND SK + SNO + Ga + Cl + KamLAND (all of the world’s data) ~3 years of GADZOOKS! (by itself)

  13. At NNN05, before I had even given my talk, John Ellis suddenly stood up and demanded of the SK people in attendance: Why haven’t you guys put gadolinium in Super-K yet? Our proposal has definitely been getting some attention: As I told him, studies are under way…

  14. …since we need to know the answers to the following questions: • What does gadolinium do the Super-K tank materials? • Will the resulting water transparency be acceptable? • How will we filter the SK water but retain gadolinium?

  15. Gadolinium R&D So, can we make it work? The total American R&D funding for this gadolinium-in-water project has reached $400,000, with additional support coming from Japan.

  16. Over the last four years there have been a large number of GdCl3-related R&D studies carried out in the US and Japan:

  17. What we really want is selective filtration. } Adding nanofiltration (NF) to ultrafiltration (UF) and reverse osmosis (RO) could make this possible.

  18. Water “Band-pass Filter” GdCl3 or Gd(NO3)3 (NF Reject) GdCl3 or Gd(NO3)3 plus smaller impurities (UF Product) Pure water plus GdCl3 or Gd(NO3)3 from detector Ultrafilter Nanofilter Impurities larger than GdCl3 or Gd(NO3)3 (UF Reject) Impurities smaller than GdCl3 or Gd(NO3)3 (NF Product) DI/RO Pure water (RO/DI product) plus GdCl3 or Gd(NO3)3 back to detector Impurities to drain (RO Reject) [Undergoing testing at UCI]

  19. On another R&D front, gadolinium has unusually strong magnetic properties – hence its widespread use as a contrasting agent in MRI scans:

  20. So - if funding allowed - it would be great to investigate using magnetic fields as a selective gadolinium filter. Method 1: Low Intensity Magnetic Separation

  21. Method 2: High Gradient Magnetic Separation

  22. IDEAL: Irvine Device Evaluating Attenuation Length Laser Pointers/ N2 Dye Laser IS/PD 6.5 m Normalized Light Intensity Water with Gd(NO3)3 Depth This is an upgrade of a 1-meter long device successfully used for IMB IS/PD [UCI High Bay Building]

  23. Attenuation Curves Data taken September 2007 in pure water [plots by M. Smy]

  24. Preliminary Measurement (Pure Water) Encouraging, but errors are yet to be determined. Will 7 meters of vertical pipe be enough? We’ll need to measure changes of less than 1% in very clear (~100 m  ~95 m absorption length) water. [plot by M. Smy]

  25. A longer lever-arm would be nice…but where to do it? 40 m Hmmmmm…

  26. That’s it for now…

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