1. Filtration Technology R&D for WATCHMAN
Mark Vagins
UC Irvine/Kavli IPMU
4th Full WATCHMAN Collaboration Meeting
Davis, CA October 30, 2014

2. To make the first phase (Gd+H2O) of WATCHMAN work, we have to:
Dissolve gadolinium sulfate (Gd2(SO4)3) in water  Easy and fast (pH control/use octahydrate form)
Remove the gadolinium efficiently and completely when desired  Also easy and fast (pH control/DI resin)
Keep pure water pure yet retain gadolinium sulfate in solution  Originally the tricky part, but after years of hardware work my “molecular band-pass” selective filtration systems are now operational (0.2 tons/hr in US since 2007) (5 tons/hr in Japan since 2010)

3. Electrical Band-Pass Filter

4. Molecular Band-Pass Filter (2007)
Ultrafilter ( nm pore size)
Nanofilter (1-10 nm pore size)
Reverse Osmosis (0.5 – 1.5 nm pore size)
Larger and smaller impurities to drain
(UF Flush + RO Reject)
Pure water
(RO product)
plus Gd2(SO4)3
Gd2(SO4)3
(NF Reject)
plus smaller impurities
(UF Product)
Impurities smaller than Gd2(SO4)3
(NF Product)
Impurities larger
than Gd2(SO4)3
(UF Reject
flushed periodically )

5. flushed periodically )
August 2009 “Band-pass Filter”
Gd2(SO4)3
(NF#1 Reject)
Gd2(SO4)3
plus smaller impurities
(UF Product)
water
plus Gd2(SO4)3
from main
tank
Ultrafilter
Nanofilter #1
Impurities larger
than Gd2(SO4)3
trapped in UF
(UF Reject
flushed periodically ) DI T O C
Nanofilter #2
Gd2(SO4)3
(NF#2 Reject)
Impurities to drain
(UF Flush)
RO #1
Pure water
(RO product)
plus Gd2(SO4)3
back to tank
Reject
Tank
RO Reject to
small tank DI
RO #2

6. The experimental setup at UCI kept getting more complicated, until we knew enough for a large-scale test: EGADS.
2007
2005
2008
2010

7. Gd Selective Filtration
Gd Removal
Ultra-
pure
Water Gd
Pre-
treat
City Water
Cleanup
Water Systems at UCI as of November 3rd, 2010
(added since then: a new material emanation soak system
and an improved ultrapure water system)

8. Prototype Selective Filtration Setup @ UCI
Membrane
Pre-Flush
Reverse
Osmosis
Nanofilter #1
Nanofilter #2
Ultrafilter

9. Selective Water+Gd Filtration System;.
Main 200-ton Water Tank with cm PMT’s + 13 HK tubes (PMT’s installed in summer of 2013)
15-ton Gadolinium
Pre-treatment
Mixing Tank
Selective Water+Gd Filtration System
11/2011

10. Technical Risk of Gd+H2O Is Retired!
Looking Down Into the 200-ton EGADS Detector; August 2013
Insert: Event Display of a Downward-Going Cosmic Ray Muon

11. To make the next phase (WbLS) of WATCHMAN work, there’s lots to do
To make the next phase (WbLS) of WATCHMAN work, there’s lots to do. In terms of the water system:
How can we keep the solution clean and clear?
Is it still okay (or even necessary) to use UV light to kill bugs?
What happens if you put the WbLS through deionization resins?
How about degasification? Can pump impellers damage WbLS?
Are the WbLS’s properties stable under extended circulation?
Adapt UCI prototype “band-pass” system (or build a new one) to investigate WbLS
I assume the first cycle of tests will be done with unloaded WbLS, i.e., no gadolinium or other stuff. Once that works, we can step up the complexity level.

12. Water-based Liquid Scintillator Filter: 1st Concept (2015)
WbLS minus huge impurities
Microfilter #1 (5000 nm pore size)
Ultrafilter #1 (10 nm pore size)
Ultrafilter #2 (5 nm pore size)
Cleaned WbLS
back to tank (UF2 product)
WbLS from tank
larger impurities
(UF1 Reject)
WbLS minus much larger impurities
Microfilter #2 (200 nm pore size)
WbLS minus larger impurities
(UF1 product)
smaller impurities
(UF2 Reject)

13. Most importantly, how soon can we get the WbLS?
If this works, great! If not, we will add and subtract components as needed until the situation improves.
N.B.: We will require at least 400 liters of WbLS at UCI (and one ton would be much better) for these circulation studies. This is due to membrane dynamics and long attenuation length measurements.
Is there any closely analogous fluid we can use while awaiting 100’s of liters of the actual WbLS?
Most importantly, how soon can we get the WbLS?

14. As soon as we receive the WbLS we can start the (most likely involved) process of figuring out how to keep it clean.
We are ready to begin our new filtration studies at UCI, and to help usher in a bright new day in particle detection.