— All Xe Events: — Xe Fiducial Anti-Coincident, Single Scatter Events: 10 / 6 / 319 / 23 mBq 10 / 10 / 461 / >80 mBq

Base Components lower activity, than these #’s Model R6041 R9288 Photo (not same scales) Dimension & QE ø5 cm x 4 cm QE 5-8% ø5 cm x 4 cm QE 20% U Series Radioactive Background [mBq/tube] Th Series 40 K 60 Co 680 mBq – 238 U equivalent (Dominated by glass seal at base) 360 90 5040 10 33.9 mBq – 238 U equivalent (Use of Kovar for most of base) 10 10 120 22.8 mBq – 238 U equivalent 3 Comment Specifically designed for ops in LiqXe TPC Evolution of 6041 R8520 (2.5 cm) 2 x3.5cm

QE >20% 15 3 0 5 R8778 ø5 cm x 12 cm QE 26% (good dyn optics) 13 23.7 mBq – 4 238 U equivalent (expect further improvement) 60 3 Gaitskell Brown University XENON Collaboration / SAGENAP Square/quad anode good fill factor (66.2%).

Columbia tested at 150K/4 atm Designed for XMASS.

Coverage Area: 49.7% Columbia tested at 150K/4 atm April 2004 v03 <11>

Kr removal (Princeton/Shutt) Charcoal Column Separation

•

85 Kr. 687 keV endpoint

b

decay

o

Rate: 280 kBq/Kg(Kr).

• XENON100: need <~0.1 ppb Kr/Xe. • Industry (SpectraGas) can produce ≈ 10 ppb Kr/Xe. • Investigating Chromatographic separation with

activated charcoal

o

Separate NSF funding at Princeton

• Separation demonstrated with 60 gm charcoal

column .

Kr Xe Kr separation ≈ 99.9 % (Preliminary) • Full processing system now being tested. • Projected performance, 1 kg charcoal column: o o o

1.8 kg Xe/day Purification ≈ 10 3 (PRELIMINARY) Use 14 stp m 3 He/ kg Xe processed.

• High purity system: completed Summer 05.

Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <12>

Material Radioactivity Screening Program

• First step (~ 6 months): o

SOLO (Soudan Low Background Screening Facility - coordinated by Brown): gamma screening for Majorana, CDMS & XENON

• Second step: o

Enlarge SOLO facility with additional ULB, 100 % eff HPGe detector,

o

Read-out electronics + software (U Florida) and operate facility jointly

• Future: o

Soudan Low Background Lab proposal - SOLO will be integrated into the proposed larger Low Background Lab

• Priority of screening (over ~ 1 year): o

PMTs: inner parts, ancillary parts, glass

o

Resistive material (RuO2) and substrate

o

PFTE of inner chamber

o

Charge collection wires, material for grid, material for ring supporting PMTs

o

Shielding materials, cables, connectors, insulation material, outer vessel

• Results from screening will be integrated into Monte Carlo background studies

Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <13>

XENON10 and beyond - Conclusion - Backgrounds

• For XENON10 current Monte Carlos indicate ~10x safety margin vs XENON10 Goal o o

Assuming 99.5% electron recoil rejection, XENON10 able to achieve XENON10 goal (20 dm evts/10kg/year)

• •

Preliminary discrimination tests will be performed above ground The rejection will need to be checked & optimized using underground operation Use of outer LXe veto region

•

Including 5 cm outer LXe veto projects backgrounds (<2 bg evt/10 kg/year) allowing XENON10 to achieve XENON100 sensitivity goal

o

Note that WIMP event rate in XENON10 module for XENON100 sensitivity goal will be only 2 WIMPs per year limited discovery potential in this lower region

• External Pb/Poly/Muon Veto Shield Design & Depth Requirements o o

Propose construction of poly/Pb shield capable of housing XENON10 or XENON100 module

•

Standard design suppresses external gammas and neutrons to below XENON100 required goals Muon Veto

• •

Muon veto required to tag neutrons generated by muons in Pb shield XENON10 & 100 goals achievable at >=2.1 kmwe with 95% veto efficiency (see full tables in Appendix)

o

High Energy Punch-through Neutrons from rock - Site Dependent

• • •

2.1 kmwe (Soudan) Shallow Site will severely limit progress beyond XENON10 goal (exp. sig. 0.3x WIMP goal) ~3.7 kmwe (Gran Sasso) provides 25x drop in flux, which is 0.1x XENON100 goal, ~XENON1T goal ~6.2 kmwe Sudbury/Homestake (Deep) provides additional 25x drop in flux, well below all goals Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <14>

Gaitskell

DOE Group Involvement

Brown/DOE Participation in the XENON Project

• Brown HEP/Particle Astrophysics Group with DOE support o o

Senior Physicist: R. Gaitskell (Prof)

•

>10 years DM R&D + Underground Operation Experience with CDMS I+II Experiments Graduate Students:

•

P. Sorensen (~2 years experience on project) / L. De Viveiros (~1 year experience on project)

• Contribution to XENON Project o o o o o o

Alternative Photo-detector Evaluation (Micro-channel Plate / (APD)) DAQ Development for 10 kg Prototype & XENON10 detector Low Background Shield and Muon Veto for Underground Operation

•

Monte Carlo Studies of radioactive backgrounds for XENON10

•

Design/Construction Background Screening (in conjunction with Florida U) of gamma activity of components

•

Current operation of SOLO (Soudan Low Background Gamma Counting Facility) -> New Soudan Low Background Lab Underground Construction / Operations Experience

•

CDMS @ Soudan Participation in management of the multi-institutional XENON project Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <17>

Proposed DOE Support for Brown Group

• Brown Group on XENON is currently PI (Gaitskell) + 2 grads

o

Currently supported through combination of OJI + Start-up (funds shared with existing CDMSII program, 2 senior grads)

• Need to add PostDoc at Brown to XENON program

o

Would have direct responsibility for DAQ and Shield on Project

• Operations Cost

o

Underground Site / Travel

• Propose Equipment Purchase for Underground Phase XENON10

o

Shields (Jul 2005 ->) $349k

•

Shield Spec would satisfy both XENON10 & XENON100 requirements

o

DAQ (Jul 2005 ->) $96k

•

Phased introduction - start with XENON10 system & then upgrade to XENON100 Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <18>

Shield Cost XENON10 / 100

• Propose to DOE the construction of a shield which will accommodate

either XENON10 and then XENON100 module

o

Inner cavity ø 67 cm x h 100 cm

o

From inside to out inner poly / Ancient Pb / Pb / Outer Poly : 20 / 5 / 18 / 30 cm

o

Purchase & Construction Jul 2005–Mar 2006 Inner Poly (20 cm / 0.7 t) Inner Ancient Pb (5 cm / 4.8 t) Outer Pb (18 cm / 23 t) Outer Poly (30 cm / 5 t) Radon Seal + Gas Handling Support Structure / Access Mechanism Engineering Design / Machining Muon Veto Plastic Scin + PMT (assumes >95% efficient) TOTAL $12k $48k $66k $69k $5k $30k $65k $119k $349k Cost of shield that can accommodate XENON10 only would be ~66% of above #’s Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <19>

DAQ Cost XENON10 / 100

• Propose to DOE for phased DAQ for XENON10 or XENON100 module

o

ADCs and associated electronics for Inner LXe PMTs, Outer LXe Veto PMTs and also Muon Veto (Plastic Scint) + associated electronics/trigger logic +Processing Farm for Events

o

Inner PMT/Outer PMT/Muon Veto # XENON10: 7 / 16 / 24 XENON100: 37 / 48 / 24 XENON10 XENON100 Fast ADCs (1 ns sampling) Inner PMTs Slow ADCs (100 ns) Inner/Outer/Veto PMTs Crates / Communication Buses Shaping Amps / Trigger Logic / DAQ Ctl DAQ / Analysis Farm + Storage Computing TOTAL $28k $19k $12k $19k $18k $96k $40k $50k $24k $28k $32k $174k Multiplexing of ADCs reduces unit count / Units from XENON10 can be used in XENON100 Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <21>

Princeton/DOE Participation in the XENON Project

• Princeton HEP Group with DOE support: o

Senior Physicists: K. McDonald (Prof), C. Lu (Research Staff).

o

HEP Group Technical Staff: Mechanical Engineer, 3 Machinists, 2 Electronics Technicians.

•

Extensive Group experience in fabricating major systems for “remote” projects: miniBooNE PMT array, BaBar drift chamber and LST, Belle glass RPC’s & SVT readout, L3 EMcal readout, …..

• Projected contributions to the XENON project: o

CsI photocathode fabrication

• •

12” and 36” vacuum deposition systems Characterization (absolute QE down to 100 nm, normalized to NIST calibrated diode)

o

Option for x-y readout via gas gain on wires

•

Minimization of detector activity

o

Option for lower-background surface test facility

•

~300 ton water tank / test of feasibility of water shield at depth

o

Design and fabrication of infrastructure for underground operation

•

Previous group experience of remote operation

o

Machining/ fabrication for 10 & 100 kg Xe modules (multi-module detector array)

o

Participation in management of the multi-institutional XENON project Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <23>

LLNL/DOE Participation in the XENON Project

• LLNL Neutrino Detector Group with DOE support o

Senior Physicists: Adam Bernstein (Staff), Chris Hagmann (Staff)

•

Low energy neutrino detection, axion experiment.

o

Engineers/PostDocs: Norm Madden , Celeste Winant (PostDoc)

• Contribution to XENON Project o

External Voltage Divider & Readout Circuits for PMTs

o •

Benefits include reduction in power consumption, heat load and radioactive burden from electronics HV system / feed-throughs for Drift field in liquid Xe

•

Drfit Field: 5 kV/cm applied field, 10-30 cm drift

o

Modeling of low energy quenching factor for nuclear recoils in liquid Xe

•

Exploits modified TRIM code (existing studies)

o

Overlap with LLNL neutrino detection program

•

Compact detectors for nuclear reactor

n

and Engineering monitoring - nuclear fuel assay / NA-22 Office of Nonproliferation Research

o •

Overlap in detector hardware, readout / leverage of ongoing DOE programs Participation in management of the multi-institutional XENON project Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <24>

Proposed DOE Support for LLNL Group

• Group Headed by Chris Hagmann / Adam Bernstein

o

Will seeking Lab support for their direct salary component for XENON

• PostDoc + Engineer

o

PostDoc (Celeste Winant, hired) full-time on project

o

Engineer (Norm Madden) part-time on XENON

o

$200k p.a.

• Equipment

o

Testing of PMT biasing schemes and resistor loadings

o

Field cage design and testing

o

$50k p.a.

Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <25>

Gaitskell

XENON Backgrounds

APPENDIX

DEPTH REQUIREMENTS NEUTRONS - MUONS IN Pb SHIELD NEUTRONS - MUONS IN ROCK

Gaitskell

Appendix: Dark Matter Depth Requirements

• Site Depth Requirement o

Dominated by need to reduce high energy (HE) neutrons (50-600 MeV), generated by muons, that cannot be moderated directly using poly

• Shallow ~2000 mwe (e.g. Soudan, 1 muons/m

2 /minute)

o

Satisfactory for 10 kg scale experiments (

s

~10 -44 cm 2 ) (HE neutrons & Veto requirements)

o o

To realize full potential of 100 kg-1 tonne experiments would require large additional active shield (>2 m thick) in order to tag HE neutrons

•

Significant risk associated with systematic failure to veto muon/HE neutron Satisfactory for cosmogenic activation

• Intermediate ~3800 mwe o o o o

Factor ~25x reduction in HE neutrons compared to shallow Significant comfort factor for 100 kg scale experiment (

s

~10 -45 cm 2 ) 1 tonne experiments could function wrt to HE neutrons from muons (

s

~10 -46 cm 2 ) using multiple scatter/capture ID of residual HE neutrons (prob. no thick active shield) Muons passing through detector array can be vetoed by muon veto (>99% being achieved)

• Deep ~6000 mwe (Further factor ~50x reduction in muon/HE neutrons) o

Eliminates any risk from HE neutrons/muons allowing (

s

~10 -46 cm 2 ) sensitivity Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <29>

Neutrons From Pb Shield, Tagging with Veto

(20 cm inner poly)

• REQUIRE MUON

VETO EFFICIENCIES

o o

Designed to tag muons that create neutrons in Pb shield Table shows required muon tagging efficiency to meet goals

o o o

Increasing poly within Pb shield from 10 cm to 20 cm reduces neutron flux from muons in Pb by ~10x Must also consider use of veto for punch through neutrons Depth requirement also constrained by punch-through neutrons Goal Muon Rate (relative) XENON10 (also CDMSII goal) XENON100 XENON1T NR Goal Rate @ 16 keVr 1/3 of total sens.

100 µdru 10 µdru 1 µdru Soudan 2.1 kmwe 1 50%* (1:2) 95% (1:20) 99.5% (1:200) Gran Sasso 3.7 kmwe x1/25 Sudbury 6.2 kmwe x1/525 Min µVeto (Raw Rate below goal) Min µVeto (Raw Rate below goal) Min µVeto (1:~1) 87% (1:8) Min µVeto (Raw Rate below goal) Min µVeto (Raw Rate below goal) * Reference number for Soudan from Monte Carlo results from CDMSII (Kamat CWRU) - 2 mdru NR @ 15 keVr, for 23 cm Pb shield & 10 cm inner poly Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <30>

Punch-through High Energy Neutrons From Rock

• Muon Veto o o o o

High Energy Neutrons 20–600 MeV generated by muons in rock of cavern Majority leave no signal in muon veto (some prospect for tagging shower, and/or possibly neutron) Poly shield has relatively little effect on flux Pb shield causes neutron multiplication! Goal Muon Rate -> Neutrons XENON10 (also CDMSII goal) XENON100 NR Goal Rate @ 16 keVr 1/3 of total sens.

100 µdru 10 µdru Soudan 2.1 kmwe 1 x1 x10 Gran Sasso 3.7 kmwe x1/25 x1/25 x1/3 Sudbury 6.2 kmwe x1/525 x1/525 x1/53 XENON1T 1 µdru x100 x3 x1/5 * Numbers show expected Nuclear Recoil (NR) single scatter event rate originating from high energy neutrons as a fraction of nominal NR goal (which is x1/3 of WIMP NR goal) Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <31>

High Energy (E>20 MeV) Neutrons from Muons

• High Energy Neutron Rates can be decreased by controlling the Muon Flux, either

by a very efficient Muon Veto or by going to greater depths

•Neutron production ~ Muon Flux o

With slight modification for hardening of muon spectrum † mean(E

m

)~ Depth 0.47

Soudan

Site * Not excavated (Multiple levels given in ft) Relative Muon Flux WIPP (2130 ft) Soudan Kamioke Boulby Gran Sasso Frejus, Homestake (4860 ft) Mont Blanc Sudbury Homestake (8200 ft) x 65 x 30 x 12 x 4 x 1 x 6 -1 x 25 x 50 -1 -1 Relative Neutron Flux >10 MeV x 45 x 25 x 11 x 4 x 1 x 6 -1 x 25 x 50 -1 -1 Gaitskell Brown University XENON Collaboration / SAGENAP

†Aglietta et.al. Nuove Cimento 12, N4, page 467

April 2004 v03 <34>

10

High Energy Neutron Background

• Cosmic Ray Muons generate High Energy Neutrons (10-2000 MeV) in Rock • MC Simulations with a typical High Energy Neutron (E = 300MeV) show that the Poly-Pb-

Poly Shield mentioned previously is very inefficient in moderating these Neutrons

o o

Conventional Shield: Only ~20% Neutron Flux Reduction If experiment is to be conducted at shallow site, we are investigating use of water shield with minimum 3m shielding in all direction - provides factor x1/100 reduction in neutron flux

0.1 n/MeV/primary

Energy Histogram of Neutrons After: 30cm Poly + 23cm Pb + 30cm Poly 3m Water 1

0.01 n/MeV /primary

Poly (30cm) Pb (23cm) Poly (30cm) 0.1

Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <35>

Gaitskell

FURTHER DETAILS OF RADIOACTIVITY WITHIN SHIELD

The simulation is run with a source that simulates the emission lines of the 20 physical PMTs. For this simulated PMT, we used the Hammamatsu R8778 tube.

2D “Hitogram” – Energy vs. Depth Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <38>

Gamma Background (Inner & Outer PMTs)

• The Inner PMT radiation is 4x below XENON10 Target and can be further reduced to 40x below XENON10 goal with the use

of a Outer LXe Veto Region Anti-coincidence cut and Multiple Scatters cut

• Hamamatsu 8778 PMTs - Measured Activity per PMT:

238 U/ 232 Th/ 40 K/ 60 Co = 13 / 4 / 60 / 3 mBq

o o o

Prototypes of alternative low background Hamamatsu PMTs within 1-1.5x of this 7 Inner Chamber PMTs / 16 Veto Region PMTs Events Detected in the Inner Chamber – DRU Event Rates averaged over the range 8-16 keVee 7 Inner PMTs 16 Outer LXe Veto PMTs XENON10 Target XENON10 Target XENON100 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <39>

PMT Gamma Background - Spatial Distribution

• The Spatial Distribution of Background Events shows that the majority of

low energy

concentrated in the surface of the Inner LXe due to placement of the Inner PMTs events are

• 7

Inner Chamber PMTs + 16 Veto PMTs -- after Xe Veto Region Coincidence Cut

o

Requires only top 2.5 cm cut for rates to be below XENON10 background goal in the entire energy spectrum

after veto and multiple-scatter cut – overall background rate can be reduced by removing the top region from the fiducial detector region.

Anti-Coincident Inner Events (8 < E < 100keV) Gaitskell Brown University XENON Collaboration / SAGENAP 040415 April 2004 v03 <40>

Inner Chamber PMT Gamma Background

• Inner PMTs -- Hamamatsu 8778 (

232 Th/ 238 U/ 40 K/ 60 Co):

o

Spatial Distribution and Energy Histogram for Events Detected in Inner Chamber XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP 040415 April 2004 v03 <41>

HV Shaping Ring Resistors

• Background Event Rate due to 10 Resistors below XENON10 Target

except in area immediately around resistor

(distance < 1cm)

• Further Background Reduction can be achieved with a x-y cut in around the resistors o o

10 Resistors in line run down the side of the inner chamber for the length of the inner Liquid Xenon region Typical Resistor Background: 238 U: 0.24mBq / 232 Th: 0.22mBq / 40 K: 0.52mBq / 60 Co: <0.02mBq

Anti-Coincident Inner Events (8 < E < 100 keV) Spatial Distribution – Top View Inner Events (8 < E < 28 keV) Energy Histogram XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP 040415 April 2004 v03 <44>

Stainless Steel Gamma Background

• Gamma Background from Stainless Steel Cryostat below XENON100 target - Liquid

Xenon Veto provides excellent shield against radiation from Cryostat

o

Double-walled Cryostat, each wall 1/8” thick, total 62kg

o

Activity (per kg): 60 Co: 23mBq / 238 U: 3.5mBq / 232 Th: 2.7mBq

Anti-Coincident Inner Events (8 < E < 100keV) Spatial Distribution Inner Chamber Events (8 < E < 28 keV) Energy Histogram XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP 040415 April 2004 v03 <45>

Effect of 5 cm LXe Veto Region - on Stainless Steel Activity

• The Multiple Scatters Cut is does not guarantee that the background rate falls below target throughout the entire Inner Chamber. o

The background rate can be reduced by fiducializing the detector – cut events from the outermost layer of the Inner Chamber and the background rate falls well below target for the entire fiducial region.

With Xe Veto Anti-Coincident Single Scatter Inner Events Without Xe Veto Single Scatter Inner Events Gaitskell Brown University XENON Collaboration / SAGENAP 040415 April 2004 v03 <47>

PMT Neutron Background

• ( ,n) Neutron Activity for the Hamamatsu R8778 PMT:

~0.11 neutrons/PMT/year

o

Estimated for 13mBq of 238 U and 4mBq of 232 Th

o

QF of 50% assumed for results below – Energy Histogram scaled to keVee

o

Background Rates are below XENON100 Target by 4 orders of magnitude Inner Events Detected XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <48>

Outer LXe Veto vs Single Xe with xyz Cut

• Simulation Results based on use of 5 cm LXe outer veto, with separate inner LXe

volume

• Outer LXe veto could be replaced by single larger LXe region. Then perform additional

xyz cuts

o

Outer LXe Veto is more conservative approach

o

Need to establish that radial cuts (outer ~5 cm) will work at necessary level in single Xe volume (z, drift depth determination looks very robust)

o

Xe used for electron drift volume requires much higher purity levels

•

Use of separate inner/outer volumes allows easier management of component locations

o

Outer LXe veto has much lower light collection efficiency requirements

•

Although amount of Xe used in outer veto is >~2.5x that of simple Xe inner expansion

o

Outer LXe veto provides additional environmental stabilization/buffer for thermal gradients on inner bath

o

Inner LXe region will have lower event rate “quieter” - reduces influence of systematics

o

Once data from XENON10 is available the use of veto in XENON100 module will also need to be evaluated Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <51>

Radon In Mine Air

• The Pb shield will be enclosed in a thick mylar (250 µm) air tight

enclosure

o

Flushed by LN2 boil off

o

This system has been tested in Soudan (SOLO) gamma background screening facility

•

Ambient Rn ~200-500 Bq/m 3 air in mine

•

Peak search (Rn daugheters) in Ge dets - undetectable for equivalent of 0.01 /keV/kg/day (low energies) sensitivity.

•

This would put activity in inner LXe below XENON1T goal Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <56>

210Pb Radiation - Gamma & Electron Background

• Pb Shielding Radiation –Effect of intrinsic

210 Pb: 30 Bq/kg (Standard Low Activity - not ancient Pb)

o

The low rate is due to the high efficiency of the Liquid Xenon Veto Region in Shielding the Inner Chamber from External Gammas Events Detected in Inner Chamber XENON10 Target XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <59>

210Pb without Liquid Xenon Veto Region

• Without outer LXe veto (5 cm) region would increase the background activity above

acceptable levels -- up to 2 orders of magnitude in the case of the Pb shield radiation:

o

Pb Radiation - Simulations done with Pb liner 2.5 cm thick (830kg), 30 Bq/kg Pb Radiation (

Without Veto Region

) Events Detected in Inner Chamber XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <60>

(

a

,n) Neutron from Rock

• ( a

,n) Neutron from Rock peak at 3MeV

• Shielding: 35cm Poly + 22.5cm Pb + 20cm Poly o

MC Simulations of moderating (alpha,n) Neutrons (T<100 keV below candidate recoil threshold)

o

Flux Reduction ~5 orders of magnitude for 50cm of Poly for total spectrum

o

Example for 3 MeV (more penetrating at higher energies due to lower elastic c-s in poly) 10 0 Relative Neutron Flux For incoming 3 MeV Neutrons (Most Penetrating)

1000

Neutron (alpha,n) Spectrum From Rock Integrated Flux (>100 keV) ~4x10^-6 /cm^2/s (Soudan) Poly (35 cm) Pb (22.5 cm) Poly (20 cm)

100 10 1 0

10 -4 0 z [cm] 70 Gaitskell Brown University XENON Collaboration / SAGENAP

1 2 3

Energy (MeV)

4 5 6

April 2004 v03 <63>

Gaitskell

Kr REMOVAL

Liquid Xe Intrinsic Background –

85

Kr (dominant concern)

•

85

o

Kr contamination in Xenon –

b

decay (Q~687 keV) Commercially Grade Purification Methods reach

10 ppb

contamination

o o

Required concentration to achieve XENON10 goal: < ~1 ppb 85 Kr events in LXe Veto Region – minimal contribution to events in inner LXe Anti-coin, Single Scatter Inner Events due to 85 Kr Decays in Inner Chamber Events Detected in Inner Chamber due to 85 Kr Decays in Veto Region 10ppb – 0.6 dru 1ppb – 60 mdru XENON100 Target 10ppt – 0.6 mdru XENON10 Target XENON10 Target XENON100 Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <66>

Kr removal (Princeton/Shutt) Charcoal Column Separation

•

85 Kr. 687 keV endpoint

b

decay

o

Rate: 280 kBq/Kg(Kr).

• XENON100: need <~0.1 ppb Kr/Xe. • Industry (SpectraGas) can produce ≈ 10 ppb Kr/Xe. • Investigating Chromatographic separation with

activated charcoal

o

Separate NSF funding at Princeton

• Separation demonstrated with 60 gm charcoal

column .

Kr Xe Kr separation ≈ 99.9 % (Preliminary) • Full processing system now being tested. • Projected performance, 1 kg charcoal column: o o o

1.8 kg Xe/day Purification ≈ 10 3 (PRELIMINARY) Use 14 stp m 3 He/ kg Xe processed.

• High purity system: completed Summer 05.

Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <68>

Gaitskell

XENON100 MODULE BACKGROUND SIMULATION SUMMARY

XENON100 Goals - Summary

• MC Background Studies show that the baseline design permits XENON100 to reach the XENON1T (20

events/1000 kg/year) sensitivity goal of 1.6 mdru (after 99.5% electron recoil discrimination) - however, single 100 module would see only 2 evts/year.

• The low background rate is achieved by additional fiducialization of the inner LXe detector, i.e. cutting

events from the top 5cm, bottom 2.5cm, and a radial cut 2.5cm thick, from the outside, + 5 cm outer veto

o o

XENON100 simulations use 55x 14mBq Inner PMTs + 64 Veto Region PMTs The MC results depicted below are Single Scatter, Xe Veto Anti-Coincident Events (Veto Region = 5cm) Spatial Distribution of Inner Chamber Events (log 10 ) Energy Histogram of Events Detected in Fiducial Inner Detector Volume XENON1T Target Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <70>

Gaitskell

DAQ SUMMARY

DAQ System - XENON10

150 Sample Pulse –- Max. Drift Distance: 15cm -> 75µs mV 100 50 0 0 7 Inner Xe PMTs 25 μs 50 75 Integrator Integrator Integrator Integrator Integrator Integrator Integrator

100ns/sample 2.4 ksample/ch SlowADC 1ns/sample 120ksample/ch FastADC SlowADC FastADC SlowADC FastADC SlowADC FastADC SlowADC FastADC SlowADC FastADC SlowADC FastADC Discrim. & Stretch

16 Outer Xe PMTs

x2 multiplex N-fold coincidence Optional Anti-coincidence SlowADC Global Trigger

24 Muon Veto Plastic Scin PMTs

x4 multiplex (Used to Veto Event in PCs) SlowADC

84 MB/s 84 MB/s PC#1 – G4 XServer Data Acqusition Event Compression 400 MB/s PC#2 – G5 XRaid 1-3 TB Storage Gbit Ethernet G5 XServer Cluster Offline Data Analysis G5 Dual 2Hz Processor Node G5 Dual 2Hz Processor Node G5 Dual 2Hz Processor Node Gaitskell Brown University XENON Collaboration / SAGENAP April 2004 v03 <72>

DAQ - Total Event Rates for Internal Components

Source 7 Inner PMTs 16 Outer PMTs HV Shaping Ring Resistors Stainless Steel Cryostat 85 Kr (@ 0.1 ppb) Lead PMT Neutrons Inner Chaber Total Event Rate for DAQ [ mHz ] 25 7.1

3.6

8.6

0.3

2.1

10 -8 Veto Region Total Event Rate for DAQ [ mHz ] 353 307 12.5

333 <0.1

563 10 -8 Total 47.6 mHz Gaitskell Brown University XENON Collaboration / SAGENAP 1.6 Hz April 2004 v03 <73>