Multi Purpose Detectors/Targets

for Low Energy Particle and AstroPhysics (LEPAP):

Stefan SchönertMPIK Heidelberg

Journées NeutrinosParis, 27/28. 11. 2003

Status & perspectives for LEPAP

Dark Matter: •direct detection of non-baryonic DM

Near future: several groups (in Europe) will define future research projects coherence & complementarity

’s as probe for astro- and geophysics:•Sun: precision meas. pp, Be7, pep, CNO stellar evolution •SN: dynamics of core collapse, relic SN •Earth: energetics of the earth

-properties: •Sun: full picture on osc. 12 •Reactor: 13(compl. to accelerator) msol² and 12 •DBD: Ł, Majorana type hierarchy, abs. mass scale•Kinematics: absolute mass scale

Is there an experimental method which can do everything ?

Isotopes/techniques for future exps.: • He (SUN) (HERON)• Ar (LB, p-decay, SUN,DM) (ICARUS,WARP)• Ne (SUN, SN, DM) (CLEAN)• Xe (DM, DBD, SUN) (XMASS, XENON, EXO,TPC)• Ge (DBD, DM) (GeLN)• Mo (DBD, SUN, SN) (MOON)• Nd (DBD)• In (SUN) (LENS)• Organic LS (SUN, REACTOR, EARTH, SN, p-decay)

(KamLAND, BOREXINO, LENA)

Eier legende Wollmilchsau (oviparous wool-milk-pig)

Specific requirements (beyond low-background)

DBD: •energy resolution•single site vs. extended evts.•tracking•daughter tagging

DBD: •energy resolution•single site vs. extended evts.•tracking•daughter tagging

DM: •low threshold•annual modulation•event-by-event discr. (recoil vs. ionization)

DM: •low threshold•annual modulation•event-by-event discr. (recoil vs. ionization)

Solar-: Bq/m3 impurities•tag •target mass > 10 t

Solar-: Bq/m3 impurities•tag •target mass > 10 t

SN dynamics: •target mass 30kt•tag

SN dynamics: •target mass 30kt•tag

Requirements sometimes orthogonal!

“A Multi-Purpose Matrix” obviously non-diagonal

Xe Ge Mo LS Ar

DM x x - - ?

DBD x x x - -

Solar x ? x x x

SN - - x x x

Geo - - - x -

p-dec. - - - x xLBL - - - - x

•Matrix obviously incomplete •No weight factor for competiveness•Not included the most successful multi-purpose detector SK

Xe for DM

Discrimination ionizing vs. recoil events by •Pulse shape of scintillation light•Electroluminescence / Scintillation

Xe

LXe

Electric Field

e-

Xe+

SC UV light

EL UV lightXe*

+Xe

Xe2*

Triplet

27ns

Singlet

3ns

2Xe2Xe

175nm175nm

Xe** + Xe

Xe2+

+e-

(recomb-ination)

Xe+

+Xe

Ionisation

Excitation

Electron/nuclear recoil

Smith, IDM2002

Xe for DM

Single phase detectors“pragmatic approach”

• Zeplin 1:• Discrimination recoil/ionization via pulse shape

• XMASS(100 kg) Reduction of background,self shielding

Xe for DM – XMASS 100kg

Low BG PMT 238U 1.8x10-2Bq232Th 6.9x10-3Bq40K 1.4x10-1Bq60Co 5.5x10-3Bq

Xe for DM - XMASS“pragmatic approach”: •Single phase detector•Minimizing external background by self shielding•Minimizing internal background by purification•Pulse shape discrimination?

800kg detector

80cm dia.

Xe for DM – XMASS 800 kg/k

g/d

ay/k

eV

pp

7Be

, 8x1021 yr

• Dominant contribution is from PMT

• Assuming further 1/10 reduction of PMTs BG

external ray (60cm, 346kg)

external ray (40cm, 100kg )

Dark matter (10-8 pb, 50GeV, 100 GeV)

Xe for DM – XMASS 800 kg sensitivity

Spin independent

spectrumSeasonal variation

Xe for DM

Two phase detectors: “sophisticated approach”Discrimination recoil vs. ionization: SC & EL

• Zeplin 1+i • XMASS (2-Phase)• XENON

Dri

ft T

ime

E

anode

e-grid

cathode

~1μ

s~4

0 ns

Gas

Liquid

-ray

Xe for DBD - XMASS

XMASS 10t too small for DBD: self shielding at Q energies insufficient

Total vol.10cm wall cut20cm30cm (FV 2.2t)30cm + ½ PMT cutEff. @300keV~50%

10 ton detector External ray BG only

(c.f

. dr

u=/k

g/da

y/ke

V)

Xe for DBD - XMASSSymbolically…

Moriyama, NOON03

Xe for DBD - XMASS

Put ＰＭＴ away

Water shield

PMT ｓ

Water shield

Scintillation light

Double focus mirror

Xe vessel + wavelength shifter

Xe vessel + wavelength shifter

Xe for DBD – EXO“very sophisticated approach”

EXO: Scintillation & Charge & Ba-tagging

Xe for Solar-

1/2 theory=8 x 1021 y

~1/100 reduction needed

2 decay of 136Xe

Detector with ~20t (10t fid. Vol)

sin22= 0.77 0.03(stat.+SSM)

Ge for DBD

• Q(76Ge) = 2.039 MeV• 5 detectors operating @ LNGS• 10.96 kg active mass (86% enriched)• 125.5 mol of 76Ge

Heidelber-Moscow Collaboration:H.V. Klapdor-Kleingrothaus, A. Dietz, L. Baudis, G. Heusser, I.V. Krivosheina, S. Kolb, B. Majorovits, H. Paes, H. Strecker, V. Alexeev, A. Balysh, A.Bakalyarov, S.T. Belyaev, V.I. Lebedev, and S. Zhukov Eur. Phys. J. A 12 (2001) 147

/20 > 1.9 1025 y

mee < 0.35 eV (90% c.l.)

76Ge: sensitivity, exposure and background

HEIDELBERG-MOSCOW Collaboration,Eur. Phys. J. A 12 (2001) 147:

M·T = 35.5 kg y, b = 6 ·10-2 (kg y keV),E ~ 4.2 keV

Sensitivity (with bgd): mee (b E / M T)1/4

0.06 / (kg year keV)

0.01

0.001

0.0001

Ge for DBD – “pragmatic approach”

Ge in liquid nitrogen/argon

Background in HD-M/IGEX dominated by external impurities Strategy to improve sensitivity (“pragmatic approach”): reduction of background: 2 ·10-1 / kg y keV (@2040 keV) 10-4 /kg y keV (operation of “naked” Gediodes in liquid nitrogen/argon Increase of mass step by step 100 kg

New Initiative at •MPIK Heidelberg: (H. Heusser, W. Hofmann, K.T. Knoepfle, S. Schönert, B. Schwingenheuer, H. Simgen)•Univ. Tuebingen•INR/ITEP•Open for new partners : France ???

LOI to LNGS in spring

New concept under study “somewhat

sofisticated approach”: Ge in liquid Ar – new ideas

• Replace LN (LN=0.8 g/cm³, 77 K)

by LAr (LN=1.4 g/cm³, 87 K)

LAr/ LN (2.615 MeV) = 0.62

• Scintillation yield: 40,000 photons / MeV Active shielding medium!(4 x organic liquid scintillator) Emission in XUV (~130 nm) – Wavelength shifting required : Organic WLS and/or Xe addition

• Essential for cosmogenic activities: Co-60, Ge-68, …• What’s about Ar-39, Ar-42 ?

LN2 shield against external background radiation

LNGS: ~ 107 /m²/d (2.6 MeV )

LN2

~6 m

10-4 (kg keV y) -1

Space @ LNGS

14.80 m

~14 m

How small could a tank be?

• Lead layer submersed in LAr

• 232Th activity of lead tank Ø

• Preliminary results 30Bq/kg

Bgd. in LAr: example 42Ar42Ar / natAr = 3·10-21 (30 Bq/kg) [Barabash et al., LAr-TPC @ LNGS]

42Ar: no vs. active suppression

, 1,2

No issue for DBD even without active suppression!

Reflector (VM2000)Wavelength shifter

Active suppression of internal bgd: example 60Co

Cosmogenic activities:•Production after completion of crystal growth•Exposure to cosmic rays above ground for 10 days: 0.18 Bq/kg [GENIUS]

60Co: no vs. active suppression

,

Reflector (VM2000)Wavelength shifter

Reduction factor ~100

External bgd: example 2.615 MeV gamma 232Th (208Tl) in lead shield

Flux from rocks(0.5 Bq / kg) and concrete (5 Bq / kg) @ LNGS: 3.5 ·107 / (m² d) [BOREXINO, Laubenstein]

New lead for shielding under study with GEMPI @ LNGS: <30 Bq / kg

232Th (208Tl): no vs. active suppr.

Lead

Simulation for 30 Bq/kg, inner-Ø: 2m, height: 2 m

Reflector (VM2000)Wavelength shifter

Ge for DM

• Conventional diodes (“pragmatic approach”): no event-by-event discrimination

reduction of background

annual modulation signal (mass!)• Cryo-detectors (“sophisticated approach”: Edelweiss,

CDMS): event-by-event discr.

heatheat

ionizationionization

ThermometerThermometer (NTD Ge)(NTD Ge)

Ge CrystalGe CrystalT~20mKT~20mK

Ge for DM – next generation cryogenic detectors

Ge for DM - GeLN

Baudis et al. NIM A 426 (1999) 425

GENIUS (12 m diameter)

Charge read-out only 300 kg y, 1E-3/ kg y keV

Ge for DBD – potential of cryodetectors

EDELWEISS: identification of alphas by their anomalous quenching factor

Conclusion: Multi-Purpose Detectors for DM/DBD/SOL ?

• Xe:

DM-det. DBD-det. Solar-det.

Solar-det DM-det (isotope separation)

• Ge:

DBD-det DM-det (convent./cryo.)

Multi-Purpose Targets!Appealing, since technological and experimental aspects similar

“MIEUX VAUT FAIRE UNE CHOSE BIEN

PLUTOT QUE D’EN FAIRE PLUSIEUR MOINS BIEN.”

Bob Lanou LowNu2003:To quote from a great philosophe Francaise:

Catherine Deneuve in “Belle de Jour”

Question of style ….

Eier legende Wollmilchsau (oviparous wool-milk-pig)

Advanced genetic engeneering: