Post on 10-Nov-2018
La Materia Oscura La Materia Oscura delldell’’Universo e i risultati Universo e i risultati delldell’’esperimento DAMAesperimento DAMA
R. Cerulli
INFN-LNGS
Gennaio 2007
Evidenze sperimentali sullEvidenze sperimentali sull’’esistenza esistenza della Materia Oscuradella Materia Oscura
Prima evidenza sperimentale dell’esistenza di Materia Oscura nell’Universo: misure delle velocità delle galassie che compongono l’ammasso COMA eseguite da Zwicky nel 1933.
Pochi anni più tardi nel 1936 Smith confermò l’esistenza di Materia Oscura studiando l’ammasso di galassie della Vergine.
Uno studio sistematico che accredita l’esistenza di Materia Oscura anche a livello di singole galassie è stato eseguito nel 1974 da due diversi gruppi, considerando molte galassie a spirale.
Queste osservazioni mostrarono che la sola componente visibile di materia non poteva dare conto delle velocità misurate e che la materia non luminosa era presente nell’ammasso in percentuale nettamente superiore rispetto alla materia visibile.
velocità di rotazione degli oggetti astrofisici di una galassia a spirale ad una distanza R dal centro della galassia.
Vediamo qui in particolare come è stato possibile evidenziare la presenza di Materia Oscura nelle galassie a spirale:
• Nel caso di sola materia luminosa, gli oggetti molto distanti dal centro della galassia, al di fuori del disco luminoso, dovrebbero avere una velocità che decresce all’aumentare di R (~1/√R).
• Le misure sperimentali mostrano, invece, che tali oggetti hanno velocità quasi costante per grandi valori di R. Tale risultato indica che deve esistere un’altra componente di materia, non visibile, detta alone oscuro.
∫=V
dVrM ρ)(In particular, spherical symmetry; mass inside a sphere:
rrGMv
rvm
rmrGM )( ;)( 2
2
2 =⇒=
rv 1
∝• Solar system or solar-system-like:
2
1 ;)(r
ρrrM ∝⇒∝• Galaxy: v about flat:
rrdrrrrrM
rrr
r 2000
22
20
02
20
0 4'''
4)( ;)( πρρπρρ ==⇒= ∫3
34 rV π=
.44)( 200
200 constrG
rrrG
rrGMv ==== ρππρ
In fact:
Altre evidenze sullAltre evidenze sull’’esistenza della esistenza della Materia OscuraMateria Oscura
Studio del moto della Grande Nube di Magellano intorno all nostra Galassia
Studio dei raggi-X emessi dai gas che circondano le galassie ellittiche
Studio della distribuzione della velocità del plasma caldo intergalattico negli ammassi
COMA Cluster
Anche la nostra Galassia (la Via Lattea) contiene al suo interno un alone oscuro che la pervade
La Via Lattea
Nella collisione tra due ammassi le galassie si comportano come un gas di particelle non interagenti mentre le nubi di plasma all’interno dell’ammasso - che si comportano come un fluido ed emettono raggi X – sono fortemente interagenti e sono sottoposte alla “pressione di ariete”
Dopo la collisione le galassie precedono il plasma rallentato dalla “pressione di ariete” e le due componenti si trovano in due regioni ben separate
Una recente prova dellUna recente prova dell’’esistenza di esistenza di Materia OscuraMateria Oscura
Il profilo del potenziale gravitazionale ottenuto Il profilo del potenziale gravitazionale ottenuto studiando il lensing gravitazionale studiando il lensing gravitazionale (contorno verde)(contorno verde) èè in in accordo con la distribuzione spaziale delle galassie e accordo con la distribuzione spaziale delle galassie e non con la distribuzione del plasmanon con la distribuzione del plasma
Questo si spiega ammettendo che la maggior parte Questo si spiega ammettendo che la maggior parte della materia presente nel sistema della materia presente nel sistema èè non luminosanon luminosa
Teorie della gravitTeorie della gravitàà modificata non sono in grado di dar modificata non sono in grado di dar conto delle osservazioniconto delle osservazioni
Collisione di due ammassi di galassie (1E0657-558 a z=0.296) avvenuta circa 100Myr fa
D. Clowe et al., astro-ph/0608407
Indicazioni dalla presenza di Materia Indicazioni dalla presenza di Materia Oscura dalla cosmologiaOscura dalla cosmologia
Le fondamenta del modello del Big Bang
La scoperta dell’espansione dell’Universo – E. Hubble (1929)
la distanza di alcune nebulose dimostrando che erano galassie esterne
le loro velocità di recessione
L’espansione dell’UniversoNel 1917 si pensava che l’Universo fosse statico e consistesse nella nostra Galassia e lo spazio vuoto che la circondava.
Negli anni venti, E. Hubble usando il nuovo telescopio da 2.5 m sul monte Wilson riuscì a misurare:
Le galassie si allontanano con una velocitàdi recessione proporzionale alla distanza
dHv 0=
H0=500 km/s/Mpc H0=71 km/s/Mpc
Galassia M31- Andromeda
La Via Lattea
Espansione generale dello spazio-tempo:Le galassie non si allontanano nello spazio ma è lo spazio stesso che si espande, trascinando con sèle galassieLe dimensioni fisiche delle galassie non cambiano→la gravità le “isola” dall’espansione
Effetto osservabile su scala intergalattica: la stella più vicina al Sole (Proxima Centauri), 4.22 anni-luce, si allontana da noi per il solo effetto dell’espansione con una velocità di soltanto 10 cm/s !!
Espansione priva di un centro:Un osservatore da una qualsiasi galassia vede la stessa espansione →l’unica legge di espansione compatibile con il Principio Cosmologico
Le fondamenta del modello del Big Bang
La scoperta dell’espansione dell’Universo – E. Hubble (1929)
Le abbondanze degli elementi leggeri: H, He, Li – G. Gamow (1948)
Le abbondanze degli elementi (i primi 3 minuti)
QUARKS Barioniprotoni, neutroni
Leptonielettroni, neutrini
Bariogenesi
Interazioni menofrequenti
1 neutrone ogni 7 protoni,
fotoni
1 secondo
Formazione dei nuclei atomici
H, He
100 secondi
non avverrà MAI PIU’nella storia dell’Universo
7
1
Gamow:La radiazione del Big Bang sopravvive ma a causa dell’espansione si raffredda
Previsione di Gamow:
Radiazione “fossile” = 5 K -268 °Cdue neutroni formano 1 nucleo di He
25% He 75% H
Le fondamenta del modello del Big Bang
La scoperta dell’espansione dell’Universo – E. Hubble (1929)
La scoperta della radiazione di fondo cosmico (CMB) – Penzias e Wilson (1965)
Le abbondanze degli elementi leggeri: H, He, Li – G. Gamow (1948)
Radiazione Fossile del Big BangViene scoperta da Penzias e Wilson (1965)
Temperatura della radiazione misurata: 3 K(banda delle micro-onde)
Riempie uniformemente il cielo!nessuna sorgente astrofisica sarebbe in grado di produrre una radiazione così uniforme!
L’immagine più antica dell’Universo 380’000 anni dopo il Big Bang la radiazione
si “libera” dalla materia ed inizia a propagarsi
La radiazione fossile mantiene “memoria”dello stato dell’Universo quando aveva lo
0.003% della sua età attualeSpettro della Radiazione
... e il lato oscuro dell’Universo?
Il miglioramento delle tecniche sperimentali ha permesso di ottenere informazioni anche sul lato oscuro dell’Universo
La radiazione cosmica di fondo ha permesso di studiare il valore della densità totale dell’Universo (Ω= ρ/ρ0) e i diversi contributi ad essa. SN 1987A vista dal telescopio Hubble
La verifica della legge di Hubble su scala sempre piùgrande permette di avere informazioni sull’espansione accelerata → costante cosmologica ed energia oscura
La nucleosintesi primordiale ha permesso di studiare quanti barioni ci sono oggi nell’Universo → necessità di materia oscura
Fluttuazione nella radiazione fossile: gli embrioni delle galassie
Le fluttuazioni di temperatura sono la traccia di fluttuazioni di densità della materia: gli embrioni delle galassie che cresceranno attraverso l’amplificazione gravitazionale
WMAP
(T2-T1)/T1=3×10-5
Nel 1992, COBE rivelò per primo piccole fluttuazioni ditemperatura (indicate da variazioni di colore)
Immagine a tutto cielodell’Universo 380000 annidopo il Big Bang.
WMAP nel 2003 ha messo a fuocol’immagine data da COBE
WMAP
Se Ω =1, è prevista la presenza di un picco a l ∼ 200
Composizione dell’Universo (barioni)Parametro di densità: Ω = densità/densità critica 6 atomi di H/m3
Ω = 1Barioni (cioè protoni, nuclei e atomi):
ΩB = 4%
La teoria cosmologica del Big Bang prevede, negli scenari teorici più accreditati, Ω=1. Verifica dalle misure sulla anisotropia di CMB
Considerando:a) la presente abbondanza di nuclei leggerib) la densità dei fotoni CMB
E’ necessaria Materia Oscura Non Barionica:- particelle relitte dall’Universo primordiale- relativistiche (Hot DM) o non-relativistiche (Cold DM)
al tempo del disaccoppiamento- Hot DM: neutrinos- Cold DM: WIMPs, axions, axion-like, ...
Composizione dell’Universo (energia oscura)
Negli ultimi 10 anni, studio della legge di Hubble su scala sempre più grande, attraverso l’utilizzo di “candele standard”: supernovae Ia (SN Ia).
informazioni sull’espansione accelerata → costante cosmologica ed energia oscura
Universo dominato dalla materia oscuraUniverso dominato da Λ
27.0 ;73.0 ≈Ω≈ΩΛ M
energia del vuoto caratterizzata da una pressione negativa
Contributo della materia (oscura e non)
PrimordialNucleosynthesis
∼ 90% of the matter in the Universe is non baryonicA large part of the Universe is in form of non baryonic Cold Dark Matter particles
73.0≈ΩΛ
““ConcordanceConcordance modelmodel””
WMAP
Supernovae IA
27.0
Ω = ΩΛ + ΩM =1.02±0.02
≈ΩMThe Universe is flat
Observations on: • light nuclei abundance
• microlensings• visible light.
ΩCDM ∼ 23%,ΩHDM,ν < 1 %ΩCDM ∼ 23%,ΩHDM,ν < 1 %
The baryons give “too small”contribution
Ωb ∼ 4% Ωb ∼ 4% Non baryonic Cold Dark
Matter is dominant
Structure formationin the Universe
Ω = densità/densità critica
6 atomi di H/m3
heavy exotic canditates, as “4th family atoms”, ...
self-interacting dark matter
Kaluza-Klein particles (LKK)
mirror dark matter
even a suitable particle not yet foreseen by theories
SUSY (R-parity conserved → LSP is stable)
neutralino or sneutrino
the sneutrino in the Smith and Weiner scenario &
a heavy ν of the 4-th family
axion-like (light pseudoscalar and scalar candidates)Heavy candidates:
• In thermal equilibrium in the early stage of Universe• Non relativistic at decoupling time <σann
.v> ~ 10-26/ΩWIMPh2 cm3s-1 → σordinary matter ~ σweak• Expected flux: Φ ~ 107 . (GeV/mW) cm-2 s-1 (0.2<ρhalo<1.7 GeV cm-3)• Form a dissipationless gas trapped in the gravitational field of the Galaxy (v ~10-3c)• neutral • stable (or with half life ~ age of Universe) • massive• weakly interacting
Relic CDM particles from primordial UniverseRelic CDM particles from primordial UniverseLight candidates: axion, axion-like produced at rest(no positive results from direct searches for relic axions with resonant cavity)
DM particles may accumulate in Sun/Earth, in galactic halo
↓annihilate
↓high energy neutrinos, g’s, anti-p and e+
↓Search for an excess over the (largely
unknown) background
detector
DMp
EARTHµ
νµ
SUN
DMp
DMp
DMp
DMp
DMp-antiDMp
Indirect detectionIndirect detection
νµ signature• Best signature from νµ
producing up-ward going µ
• Underground, underwater, underice detectors
γ signature• Search for quasi-
monoenergetic γ’s in cosmic rays
• Space detectors
antimatter signature
• Search for antimatter excess in cosmic rays
• Space detectors
Similar searches can offer only results, which strongly depend on the background modeling and on the
astrophysical, particle and nuclear Physics assumptions
La rivelazione diretta delle particelle di La rivelazione diretta delle particelle di Materia OscuraMateria Oscura
• Questa tecnica si basa (principalmente) sullo studio dell’interazione elastica delle particelle di DM con i nuclei che costituiscono il rivelatore utilizzato.
• A seguito di una interazione elastica di una particella con un nucleo, questo rincula.
• L’energia di rinculo del nucleo è, quindi, la grandezzamisurata.
• Si possono utilizzare rivelatori a scintillazione (NaI(Tl), LXe,CaF2(Eu),etc.), a ionizzazione (Ge, Si), Bolometri (TeO2, Ge)
DMp Nucleo
DMp
Energia di rinculo
Diffusione su nuclei-bersaglio
Conversione in radiazione elettromagnetica
• A seguito della conversione della particellanell’interazione con il nucleo, vengono prodotti γ, raggi-X o e- con energia circa uguale alla sua massa
aγ
e-
X-ray
NOTA: i segnali prodotti da questi candidati sono perduti in esperimenti basati sulle procedure di reiezione del fondo elettromagnetico
Diffusione elastica sul nucleo con eccitazione di elettroni legati
• Si misura l’energia di rinculo del nucleo e la radiazione e.m. prodotta
Main recipes for the Dark Matter particle direct detection
- Background at LNGS:muons → 0.6 µ/(m2h)neutrons → 1.08·10-6 n/(cm2s) thermal
1.98·10-6 n/(cm2s) epithermal0.09·10-6 n/(cm2s) fast (>2.5 MeV)
Radon in the hall → ≈30 Bq/m3
- Internal Background:selected materials (Ge, NaI, AAS, MS, ...)
ShieldingPassive shield: Lead (Boliden [< 30 Bq/kg from 210Pb], LC2 [<0.3 Bq/kg from 210Pb], lead from old roman galena), OFHC Copper, Neutron shield (low A materials, n-absorber foils)Active shield: Low radio-activity NaI(Tl) surrounding the detectors
• Underground site• Low bckg hard shields
against γ’s, neutrons• Lowering bckg: selection of
materials, purifications, growing techniques, ...
• Rn removal systems
Background sources
Example of background reduction
during many years of work
Reduction from the
underground site
Example of the effect of a passive shield
• Experimental vs Expected spectra (with or without bckg rejection )
+
by model: σp
MW
σ nucl
eus
Excluded atgiven C.L.
Exclusion plot
An exclusion plot not an absolutelimit. When different target nuclei, no absolute comparison possible.
• No discovery potentiality
• Uncertainties in the exclusion plots and in their comparison
• Warning: limitations in the recoil/background discrimination (always not event by event): PSD (τ of the pulse depends on the particle) in scintillators(NaI(Tl), LXe), Heat/Ionization (Ge), Heat/Scintillation (CaF2(Eu), CaWO4).
several assumptions and modeling required
experimental and theoretical uncertainties generally not included in calculations
The The ““traditionaltraditional”” approachapproach
To have a potentiality of discovery a model independent signature is needed !
A model independent signature is needed
Directionality Correlation of nuclear recoil track with
Earth's galactic motion due to the distribution of Dark
Matter particles velocities very hard to realize
Nuclear-inelastic scatteringDetection of γ’s emitted by
excited nucleus after a nuclear-inelastic scattering.
very large exposure and very low counting rates hard to realize
Diurnal modulation Daily variation ofthe interaction rate due to different Earth depth crossed by the Dark Matter particles
only for high σ
Annual modulation Annual variation of the interaction rate due to Earth motion around the Sun.
at present the only feasible one
The annual modulation: a model independent signature for the The annual modulation: a model independent signature for the investigation of Dark Matter particles component in the galacticinvestigation of Dark Matter particles component in the galactic halohalo
With the present technology, the annual modulation is the main mWith the present technology, the annual modulation is the main model independent signature for the DM odel independent signature for the DM signal. Although the modulation effect is expected to be relativsignal. Although the modulation effect is expected to be relatively smallely small a suitable a suitable largelarge--mass, lowmass, low--radioactiveradioactive setset--up with an efficient control of the running conditions would poiup with an efficient control of the running conditions would point out its presencent out its presence..
December30 km/s
~ 232 km/s60°
June30 km/s
Drukier, Freese, Spergel PRD86Freese et al. PRD88 • vsun ~ 232 km/s (Sun velocity in the halo)
• vorb = 30 km/s (Earth velocity around the Sun)• γ = π/3• ω = 2π/T T = 1 year• t0 = 2nd June (when v⊕ is maximum)
Expected rate in given energy bin changes because the annual motion of the Earth around the Sun moving in the Galaxy
v⊕(t) = vsun + vorb cosγcos[ω(t-t0)]
)](cos[)]([ 0,,0 ttSSdEdEdRtS km
EkR
Rk
k
−+≅= ∫∆
ωη
Requirements of the annual modulationRequirements of the annual modulation
1)1) Modulated rate according cosineModulated rate according cosine
2)2) In a definite low energy rangeIn a definite low energy range
3)3) With a proper period (1 year)With a proper period (1 year)
4)4) With proper phase (about 2 June)With proper phase (about 2 June)
5)5) For single hit events in a multiFor single hit events in a multi--detector setdetector set--upup
6)6) With modulation amplitude in the region of maximal sensitivity With modulation amplitude in the region of maximal sensitivity must be <7% for usually adopted halo distributions, but it can must be <7% for usually adopted halo distributions, but it can be larger in case of some possible scenarios
To mimic this signature, spurious To mimic this signature, spurious effects and side reactions must effects and side reactions must not only not only -- obviously obviously -- be able to be able to account for the whole observed account for the whole observed modulation amplitude, but also modulation amplitude, but also to satisfy contemporaneously all to satisfy contemporaneously all
the requirementsthe requirements
be larger in case of some possible scenarios
DAMA/R&DDAMA/LXe low bckg DAMA/Ge
for sampling meas.
DAMA/NaI
DAMA/LIBRA
http://people.roma2.infn.it/dama
Roma2,Roma1,LNGS,IHEP/Beijing
DAMA/LXe: results on rare processes DAMA/LXe: results on rare processes Dark Matter Investigation• Limits on recoils investigating the DMp-129Xe
elastic scattering by means of PSD • Limits on DMp-129Xe inelastic scattering• Neutron calibration• 129Xe vs 136Xe by using PSD → SD vs SI signals to
increase the sensitivity on the SD component
PLB436(1998)379PLB387(1996)222, NJP2(2000)15.1PLB436(1998)379, EPJdirectC11(2001)1
foreseen/in progress
Other rare processes:• Electron decay into invisible channels• Nuclear level excitation of 129Xe during CNC processes• N, NN decay into invisible channels in 129Xe
• Electron decay: e- → νeγ• 2β decay in 134Xe
• Improved results on 2β in 134Xe,136Xe• CNC decay 136Xe → 136Cs• N, NN, NNN decay into invisible channels in 136Xe
Astrop.Phys5(1996)217
PLB465(1999)315
PLB493(2000)12
PRD61(2000)117301
PLB527(2002)182
PLB546(2002)23
Beyond the Desert (2003) 365
EPJA27 s01 (2006) 35
NIMA482(2002)728
• 2β decay in 136Ce and in 142Ce• 2EC2ν 40Ca decay• 2β decay in 46Ca and in 40Ca• 2β+ decay in 106Cd• 2β and β decay in 48Ca• 2EC2ν in 136Ce, in 138Ce
and α decay in 142Ce• 2β+ 0ν and EC β+ 0ν decay in 130Ba• Cluster decay in LaCl3(Ce)
• Particle Dark Matter search with CaF2(Eu)
DAMA/R&D setDAMA/R&D set--up: results on rare processesup: results on rare processesNPB563(1999)97, Astrop.Phys.7(1997)73
Il Nuov.Cim.A110(1997)189
Astrop. Phys. 7(1999)73
NPB563(1999)97
Astrop.Phys.10(1999)115
NPA705(2002)29
NIMA498(2003)352
NIMA525(2004)535
NIMA555(2005)270
Il Nuovo Cim. A112 (1999) 545-575, EPJC18(2000)283, Riv. N. Cim. 26 n.1 (2003)1-73, IJMPD13(2004)2127
• Reduced standard contaminants (e.g. U/Th of order of ppt) by material selection and growth/handling protocols.
• PMTs: Each crystal coupled - through 10cm long tetrasil-B light guides acting as optical windows - to 2 low background EMI9265B53/FL (special development) 3” diameter PMTs working in coincidence.
• Detectors inside a sealed Cu box maintained in HP Nitrogen atmosphere in slight overpressure
•• data taking of each annual cycledata taking of each annual cycle starts from autumn/winter (when cosω(t-t0)≈0) toward summer (maximum expected).•• routine calibrationsroutine calibrations for energy scale determination, for acceptance windows efficiencies by means of radioactive sources
each ~ 10 days collecting typically ~105 evts/keV/detector + intrinsic calibration from 210Pb (~ 7 days periods) + periodical Compton calibrations, etc.
•• continuous oncontinuous on--line monitoring of all the running parametersline monitoring of all the running parameters with automatic alarm to operator if any out of allowed range.
Main procedures of the DAMA data taking for the DMp annual modulMain procedures of the DAMA data taking for the DMp annual modulation signatureation signature
•Very low radioactive shields: 10 cm of Cu, 15 cm of Pb + shield from neutrons: Cd foils + polyethylene/paraffin+ ~ 1 m concrete moderator largely surrounding the set-up
• Installation sealed: A plexiglas box encloses the whole shield and is also maintained in HP Nitrogen atmosphere in slight overpressure. Walls, floor, etc. of inner installation sealed by Supronyl (2×10-11 cm2/s permeability).Three levels of sealing.
• Installation in air conditioning + huge heat capacity of shield
•Calibration using the upper glove-box (equipped with compensation chamber) in HP Nitrogen atmosphere in slight overpressure calibration → in the same running conditions as the production runs.
•Energy and threshold: Each PMT works at single photoelectron level. Energy threshold: 2 keV (from X-ray and Compton electron calibrations in the keV range and from the features of the noise rejection and efficiencies). Data collected from low energy up to MeV region, despite the hardware optimization was done for the low energy
•Pulse shape recorded over 3250 ns by Transient Digitizers.
•Monitoring and alarm system continuously operating by self-controlled computer processes.
+ electronics and DAQ fully renewed in summer 2000
total exposure collected in 7 annual cyclestotal exposure collected in 7 annual cycles
Results on DM particles:
107731 kg×d107731 kg×d
DAMA/NaI(Tl)~100 kgDAMA/NaI(Tl)~100 kgResults on rare processes:
•• PSDPSD PLB389(1996)757•• Investigation on diurnal effectInvestigation on diurnal effect
N.Cim.A112(1999)1541•• Exotic Dark Matter search Exotic Dark Matter search PRL83(1999)4918•• Annual ModulationAnnual Modulation SignatureSignature
PLB424(1998)195, PLB450(1999)448, PRD61(1999)023512, PLB480(2000)23,EPJ C18(2000)283, PLB509(2001)197, EPJ C23 (2002)61, PRD66(2002)043503, Riv.N.Cim.26 n.1 (2003)1-73, IJMPD13(2004)2127, IJMPA21(2006)1445),EPJC47(2006)263
• Possible Pauli exclusion principle violation• CNC processes• Electron stability and non-paulian transitions in
Iodine atoms (by L-shell) • Search for solar axions• Exotic Matter search• Search for superdense nuclear matter• Search for heavy clusters decays
PLB408(1997)439PRC60(1999)065501
PLB460(1999)235PLB515(2001)6EPJdirect C14(2002)1EPJA23(2005)7 EPJA24(2005)51
Performances: N.Cim.A112(1999)545-575, EPJC18(2000)283, Riv.N.Cim.26 n. 1(2003)1-73, IJMPD13(2004)2127
data taking completed on July 2002data taking completed on July 2002
from the fit with all the parameters free:from the fit with all the parameters free:A = (0.0200 A = (0.0200 ±± 0.00320.0032) ) cpd/kg/keVcpd/kg/keVtt00 = (140 = (140 ±± 22) d 22) d T = (1.00 T = (1.00 ±± 0.01) y0.01) y
model independent evidence of a particle Dark Matter component in the galactic halo at 6.3σ C.L.
model independent evidence of a particle Dark Matter model independent evidence of a particle Dark Matter component in the galactic halo at 6.3component in the galactic halo at 6.3σσ C.L.C.L.
Power Power spectrumspectrum
Principal mode → 2.737 · 10-3 d-1 ≈ 1 y-1
P(A=0) = 7P(A=0) = 7⋅⋅1010--44
Solid line: tSolid line: t00 = 152.5 days, T = 1.00= 152.5 days, T = 1.00 yearsyearsfrom the fit: from the fit:
A = (0.0192 A = (0.0192 ±± 0.00310.0031) ) cpd/kg/keVcpd/kg/keV
All the peculiarities of the signature satisfiedAll the peculiarities of the All the peculiarities of the signature satisfiedsignature satisfied No systematics or side reaction able to account
for the measured modulation amplitude and to satisfy all the peculiarities of the signature
No No systematicssystematics or side reaction able to account or side reaction able to account for the measured modulation amplitude and to for the measured modulation amplitude and to satisfy all the peculiarities of the signaturesatisfy all the peculiarities of the signature
2-6 keV
6-14 keV
Experimental residual rate of the single hit events in 2-6 keV over 7 annual cycles
Acos[ω(t-t0)]
Final model independent result by DAMA/NaIFinal model independent result by DAMA/NaI
2-6 keV
experimental residual rate of the multiple hit events (DAMA/NaI-6 and 7) in the 2-6 keV energy interval: A = -(3.9±7.9) ·10-4 cpd/kg/keV
experimental residual rate of the single hit events (DAMA/NaI-1 to 7) in the 2-6 keV energy interval:A = (0.0195±0.0031) cpd/kg/keV
Multiple hits events = Dark Matter particle “switched off”
7 annual cycles: total exposure ~ 1.1 x 105 kg×dRiv. N. Cim. 26 n. 1 (2003) 1-73, IJMPD 13 (2004) 2127
Time (day)
What we can also learn from the multiple/single hit rates. A toy model
2singlemult 4 rNRR TT
πσ
⋅=
The 8 NaI(Tl) detectors in (anti-)coincidence have 3.1×1026 nuclei of Na and 3.1×1026 nuclei of Iodine. N= 3.1×1026
( )INaIINaNaTT NNNN σσσσσ +⋅=+=
( )2singlemult 4 med
INa
rNRR
⋅+⋅
⋅≈π
σσ rmed ∼ 10-15 cm
;cpd/kg/keV 10cpd/kg/keV 10)84( 34 −− <⋅±−≈multA
;cpd/kg/keV 102 2single
−⋅≈A
2
single
105 −⋅<AAmult
( )2
single 4 med
INamult
rN
AA
⋅+⋅
≈π
σσ
barn 2.0<+ INa σσ
Therefore, the ratio of the modulation amplitudes is:
From the experimental data:
Hence:
In conclusion, the particle (A) responsible of the modulation in the single-hit rate and not in the multiple-hit rate must have:
Since for fast neutrons the sum of the two cross sections (weighted by 1/E, ENDF/B-VI) is about 4 barns:
A A’
It
What about the nuclear cross sections of the particle(A) responsible of the modulation in the single-hit rate and not in the multiple-hit rate?
(A) cannot be a fast neutron
Pressure
Temperature
Radon outside the shield
Nitrogen Flux hardware ratean example:DAMA/NaI-6
Running conditions stable at level < 1%
Distribution of some parameters
All the measured amplitudes well compatible with zero
+ none can account for the observed effect
outside the shield
(to mimic such signature, spurious effects and side reactions must not only be able to
account for the whole observed modulation amplitude, but also simultaneously satisfy all
the 6 requirements)
Running conditionsRunning conditions
[for details and for the other annual cycles see for example: PLB424(1998)195, PLB450(1999)448, PLB480(2000)23, RNC26(2003)1-73, EPJC18(2000)283, IJMPD13(2004)2127]
Modulation amplitudes obtained by fitting the time behaviours of main running parameters, acquired with the production data, when including a modulation term as in the Dark Matter particles case.
Can a hypothetical background modulation Can a hypothetical background modulation account for the observed effect?account for the observed effect?
Integral rate at higher energy (above 90 keV), R90
Energy regions closer to that where the effect is observed e.g.:Mod. Ampl. (6-10 keV): -(0.0076 ± 0.0065), (0.0012 ± 0.0059) and (0.0035 ± 0.0058) cpd/kg/keV for DAMA/NaI-5, DAMA/NaI-6 and DAMA/NaI-7; → they can be considered statistically consistent with zeroIn the same energy region where the effect is observed:no modulation of the multiple-hits events (see elsewhere)
• Fitting the behaviour with time, adding a term modulated according period and phase expected for Dark Matter particles:
→consistent with zero + if a modulation present in the whole energy spectrum at the level found in the lowest energy region → R90 ∼ tens cpd/kg → ∼ 100 σ far away
No modulation in the background:these results also account for the bckg component due to neutrons
No modulation in the background:these results also account for the bckg component due to neutrons
• R90 percentage variations with respect to their mean values for single crystal in the DAMA/NaI-5,6,7 running periods
Period Mod. Ampl.DAMA/NaI-5 (0.09±0.32) cpd/kgDAMA/NaI-6 (0.06±0.33) cpd/kgDAMA/NaI-7 -(0.03±0.32) cpd/kg
→ cumulative gaussian behaviour with σ ≈ 0.9%, fully accounted by statistical considerations
(see Riv. N. Cim. 26 n. 1 (2003) 1-73, IJMPD13(2004)2127 and references therein)
Summary of the results obtained in the investigations of Summary of the results obtained in the investigations of possible systematics or side reactionspossible systematics or side reactions
Source Main comment Cautious upperlimit (90%C.L.)
RADON Sealed Cu box in HP Nitrogen atmosphere,etc <0.2% Smobs
TEMPERATURE Installation is air conditioned+ <0.5% Smobs
detectors in Cu housings directly in contact with multi-ton shield→ huge heat capacity+ T continuously recorded
NOISE Effective noise rejection <1% Smobs
ENERGY SCALE Periodical calibrations + continuous monitoring <1% Smobs
of 210Pb peakEFFICIENCIES Regularly measured by dedicated calibrations <1% Sm
obs
BACKGROUND No modulation observed above 6 keV + this limit <0.5% Smobs
includes possible effect of thermal and fast neutrons+ no modulation observed in the multiple-hits events in 2-6 keV region
SIDE REACTIONS Muon flux variation measured by MACRO <0.3% Smobs
+ even if larger they cannot satisfy all the requirements of annual modulation signature
Thus, they can not mimic the observed annual
modulation effect
No other experiment whose result can be directly compared in model independent way is available so far
Presence of modulation for 7 annual cycles at ~6.3σC.L. with the proper distinctive features of the
signature; all the features satisfied by the data over 7 independent experiments of 1 year each one
Absence of known sources of possible systematics and side processes able to
quantitatively account for the observed effect and to contemporaneously satisfy the many
peculiarities of the signature
To investigate the nature and coupling with ordinary matter of the possible DM candidate(s), effective energy and time correlation analysis of the events has to be performed within given model frameworks
Summary of the DAMA/NaI Model Independent result
astrophysical models: ρDM, velocity distribution and its parameters
nuclear and particle Physics models
experimental parameters
THUSuncertainties on models
and comparisons
e.g. for WIMP class particles: SI, SD, mixed SI&SD, preferred inelastic, scaling laws on cross sections, form factors and related parameters, spin factors, halo models, etc.
+ different scenarios+ multi-component?
+
Corollary quests for candidate(s)
First case: the case of DM particle scatterings on target-nuclei.The recoil energy is the detected quantity
DM particle-nucleus elastic scattering SI+SD differential cross sections:gp,n(ap,n) effective DM particle-nucleon couplings
<Sp,n> nucleon spin in the nucleus
F2(ER) nuclear form factors
mWp reduced DM particle-nucleon mass
dσdER
(v,ER) = dσdER
⎛
⎝ ⎜ ⎞
⎠ ⎟
SI
+ dσdER
⎛
⎝ ⎜ ⎞
⎠ ⎟
SD
=
2GF2mN
πv2 Zgp + (A− Z)gn[ ]2FSI
2 (ER) + 8 J +1J
ap Sp + an Sn[ ]2FSD
2 (ER )⎧ ⎨ ⎩ ⎫ ⎬ ⎭
Differential energy distribution depends on the assumed scaling laws, nuclear form factors, spin factors, free parameters (→ kind of coupling, mixed SI&SD, pure SI, pure SD, pure SD through Z0 exchange, pure SD with dominant coupling on proton, pure SD with dominant coupling on neutron, preferred inelastic, ...), on the assumed astrophysical model (halo model, presence of non-thermalized components, particle velocity distribution, particle density in the halo, ...) and on instrumental quantities (quenching factors, energy resolution, efficiency, ...)
Note: not universal description. Scaling laws assumed to define point-like cross sections from nuclear ones. Four free parameters: mW, σSI, σSD , tgθ =
an
ap
Preferred inelastic DM particle-nucleus scattering: χ-+N→ χ++NSm/S0 enhanced with respect to the elastic scattering case
• DM particle candidate suggested by D. Smith and N. Weiner (PRD64(2001)043502)
• Two mass states χ+ , χ- with δ mass splitting• Kinematical constraint for the inelastic scattering of
χ- on a nucleus with mass mN becomes increasingly severe for low mN 1
2µv2 ≥ δ ⇔ v ≥ vthr =
2δµ
Three free parameters: mW, σp, δ
Ex. mW =100 GeVmN µ70 41
130 57
Spin Independent
2( ) /5nqre−
2 21 2( ) ( )(1 )n nqr qrAe A eα α− −+ −
Helm
charge spherical distribution
from Ressell et al.
from Helm
2 21 2( ) ( )(1 )n nqr qrAe A eα α− −+ −
Smith et al.,Astrop.Phys.6(1996) 87
2( ) /5nqre−
“thin shell”distribution
Spin Dependent
Examples of different Form Examples of different Form Factor for Factor for 127127I available I available in literaturein literature
• Take into account the structure of target nuclei
• In SD form factor: no decoupling between nuclear and Dark Matter particles degrees of freedom; dependence on nuclear potential.
Similar situation for all the target nuclei considered
in the field
The Spin FactorThe Spin FactorSpin Factors for some target-nuclei calculated in simple different models
Spin factor = Λ2J(J+1)/ax2
(ax= an or ap depending on the unpaired nucleon)
Spin Factors calculated on the basis of Ressell et al. for some of the possible θvalues considering some target nuclei and two different nuclear potentials
Spin factor = Λ2J(J+1)/a2
Large differences in the measured counting rate can be expected:• when using target nuclei sensitive to the SD component of the interaction (such as e.g. 23Na and 127I) with the respect
to those largely insensitive to such a coupling (such as e.g. natGe, natSi, natAr, natCa, natW, natO);• when using different target nuclei although all – in principle – sensitive to such a coupling, depending on the
unpaired nucleon (compare e.g. odd spin isotopes of Xe, Te, Ge, Si, W with the 23Na and 127I cases).
tgθ =an
ap
(0≤θ<π)
Astrop. Phys.3(1995)361
Quenching factors, q, measured by neutron sources or by neutron beams for some detectors and nuclei
assumed 1 (but 0.91 ±0.03 in astro-ph/0607502 )
• differences are often present in different experimental determinations of q for the same nuclei in the same kind of detector
• e.g. in doped scintillators q depends on dopant and on the impurities/trace contaminants; in LXe e.g.on trace impurities, on initial UHV, on presence of degassing/releasing materials in the Xe, on thermodynamical conditions, on possibly applied electric field, etc.
• Some time increases at low energy in scintillators (dL/dx)
recoil/electron response ratio measured with a neutron source or at a neutron generator
Ex. of different q determinations for Ge
Quenching factorQuenching factor
Consistent Halo ModelsConsistent Halo Models• Isothermal sphere ⇒ very simple but unphysical halo model; generally not considered• Several approaches different from the isothermal sphere model: Vergados PR83(1998)3597,
PRD62(2000)023519; Belli et al. PRD61(2000)023512; PRD66(2002)043503; Ullio & KamionkowskiJHEP03(2001)049; Green PRD63(2001) 043005, Vergados & Owen astroph/0203293, etc.
Models accounted in the following(Riv. N. Cim. 26 n.1 (2003)1-73 and previously in PRD66(2002)043503 )
10 )50220( −⋅±= skmv
⊕⊕ ⋅≤≤⋅ MMM vis1010 106101
00 2.1)100(8.0 vkpcrvv rot ⋅≤=≤⋅
• Needed quantities
→ DM local density ρ0 = ρDM (R0 = 8.5 kpc) → local velocity v0 = vrot (R0 = 8.5kpc) → velocity distribution ( )f vr
• Allowed ranges of ρ0 (GeV/cm3) have been evaluated for v0=170,220,270 km/s, for each considered halo density profile and taking into account the astrophysical constraints:
NOT YET EXHAUSTIVE AT ALL
Halo modelingHalo modeling• Needed quantities for Dark Matter direct searches:
→ DM local density ρ0 = ρDM (R0 = 8.5 kpc) → local velocity v0 = vrot (R0 = 8.5kpc) → velocity distribution ( )f vr
Isothermal sphere: the most widely used (but not correct) model
density profile: gravitational potential:
→ Maxwellian velocity distribution
2( )DM r rρ −∝ 20 log( )rΨ ∝
2
0 21r
vv
φβ = −Spherical ρDM with non-isotropic velocity dispersion →
Axisymmetric ρDM → q flatness
2 22 20
0 2( , ) log2 cv zr z R r
q⎛ ⎞
Ψ = − + +⎜ ⎟⎝ ⎠
Triaxial ρDM → p,q,δ2 2 2
200 2 2( , , ) log
2v y zx y z x
p q⎛ ⎞
Ψ = − + +⎜ ⎟⎝ ⎠
δ = free parameter → in spherical limit (p=q=1) quantifies the anisotropy of the velocity dispersion tensor
2
2
22r
vv
φ δ+=
2 2 20
2 2 2
3( )4 ( )
cDM
c
v R rrG R r
ρπ
+=
+
22 20
0 ( ) log( )2 cvr R rΨ = − +
22 2
2 2( )( )rot c
c
rv r vR r
=+
2 2
2 2 ( 4) / 2
3 (1 )( )4 ( )
a c cDM
c
R R rrG R r
β
β
β βρπ +
Ψ + −=
+ 0 2 2 / 2( ) , ( 0)( )
a c
c
RrR r
β
β βΨΨ = ≠
+
22
2 2 ( 2) / 2( )( )
a crot
c
R rv rR r
β
β
β+
Ψ=
+
( ) /
0 00
1 ( / )( )1 ( / )DM
R R arr r a
β γ αγ α
αρ ρ−
⎡ ⎤+⎛ ⎞= ⎜ ⎟ ⎢ ⎥+⎝ ⎠ ⎣ ⎦
Evans’logarithmic
Evans’power-law
Spherical ρDM, isotropic velocity dispersion
Others:
00 2.1)100(8.0 vkpcrvv rot ⋅≤=≤⋅⊕⊕ ⋅≤≤⋅ MMM vis1010 1061011
0 )50220( −⋅±= skmvConstraining the models
DM particle with elastic SI&SD interactions(Na and I are fully sensitive to SD interaction, on the contrary of e.g. Ge and Si) Examples of slices of the allowed volume in the space (ξσSI, ξσSD, mW, θ) for some of the possible θ (tgθ =an/ap with 0≤θ<π) and mW
Few examples of corollary quests for the WIMP class(Riv. N.Cim. vol.26 n.1. (2003) 1-73, IJMPD13(2004)2127)
Region of interest for a neutralino in supersymmetric schemes where assumption on gaugino-mass unification at GUT is released and for “generic” DM particle
DM particle with dominant SI coupling
Regions above 200 GeV allowed for low v0, for every set of parameters’ values and for Evans’logarithmic C2 co-rotating halo models
volume allowed in the space (mW,ξσSD,θ); here example of a slicefor θ=π/4 (0≤θ<π)
not exhaustive+ differentscenarios?
DM particle with preferred inelastic interaction: W + N → W* + N (Sm/S0 enhanced): examples of slices of the allowed volume in the space (ξσp, mW,δ)[e.g. Ge disfavoured]
DM particle with dominant SD coupling
higher mass region allowed for low v0,
every set of parameters’ values
and the halo models: Evans’
logarithmic C1 and C2 co-rotating,
triaxial D2 and D4 non-rotating, Evans
power-law B3 in setA
Most of these allowed volumes/regions areunexplorable e.g. by Ge, Si,TeO2, Ar,
Xe, CaWO4 targets
Model dependent lower bound on neutralino mass as derived from LEP data in supersymmetricschemes based on GUT assumptions (DPP2003)
An example of the effect induced by a nonAn example of the effect induced by a non--zero zero SD component on the allowed SI regionsSD component on the allowed SI regions
• Example obtained considering Evans’ logarithmic axisymmetric C2 halo model with v0 = 170 km/s, ρ0 max at a given set of parameters
• The different regions refer to different SD contributions with θ=0
a) σSD = 0 pb; b) σSD = 0.02 pb;c) σSD = 0.04 pb; d) σSD = 0.05 pb;e) σSD = 0.06 pb; f) σSD = 0.08 pb;
• There is no meaning in bare comparison between regions allowed in experiments sensitive to SD coupling and exclusion plots achieved by experiments that are not.
• The same is when comparing regions allowed by experiments whose target-nuclei have unpaired proton with exclusion plots quoted by experiments using target-nuclei with unpaired neutron where θ ≈ 0 or θ ≈ π.
A small SD contribution ⇒drastically moves the allowed region in the plane (mW, ξσSI) towards lower SI
cross sections (ξσSI < 10-6 pb)
Similar effect for whatever considered model framework
Supersymmetric expectations in MSSM
•Assuming for the neutralino a dominant purely SI coupling
•when releasing the gaugino mass unification at GUT scale:
M1/M2≠0.5 (<); (where M1 and M2 U(1) and SU(2) gaugino masses)
low mass configurations are obtained
figure taken from PRD69(2004)037302
scatter plot of theoretical configurations vs DAMA/NaI allowed region in the given model frameworks for the total DAMA/NaI exposure (area inside the green line);
(for previous DAMA/NaI partial exposure see PRD68(2003)043506)
Some open scenarios on astrophysical Some open scenarios on astrophysical aspectsaspects
In the galactic halo, fluxes of Dark Matter particles with dispersion velocity relatively low are expected:
some relics of the hierarchical assembly of the Milky Way are already observed in the visible: Sagittarius dwarf galaxy since 1994, Canis Major galaxy early discovered…
This scenario foreseen streams of Dark Matter particles with lowvelocity dispersion, very interesting for direct detection: Sm/S0enhanced in A.M., new signature for streams
La galassia La galassia ““nananana”” Sagittario (Sgr) e lSagittario (Sgr) e l’’alone di materia oscuraalone di materia oscura……Nel 1994 –1995 e’ stato osservato un nuovo oggetto “Sagittarius Dwarf Elliptical Galaxy” nelle vicinanze dellaVia Lattea, nella direzione del centrogalattico, ed in posizione opposta ad essorispetto al Sistema Solare
La direzione di moto della Sgr era molto diversa da quella degli altri oggetti luminosinella Via Lattea, così si è scoperto che le stelle osservate appartenevano ad una galassianana satellite della Via Lattea, che sta per essere catturata. La galassia nana ha assuntouna forma molto allungata a causa delle forze di marea subite durante le circa 10 rivoluzioni effettuate attorno alla Via Lattea.
La galassia sferoidale La galassia sferoidale ““nananana”” Sagittario, satellite della Via LatteaSagittario, satellite della Via Lattea
(Ibata et al. 1994)(Ibata et al. 1994)
il Sole disterebbepochi kpc dalcentro della coda trainante...:
E’ atteso un flusso di particelle costituenti la materia oscuradell’alone galattico di Sgr, convelocità ortogonale al nostropiano galattico di circa 300 km/s.
da astro-ph/0309279:
sun
sgr
stream
Densità dello stream attesa:[1 -- 80] 10-3 GeV/cm3 (0.3-25)% di ρhalo
Velocità locale media dello stream ricavata dalle misure su 8 stelle locali attribuite alla coda trainante di Sgr:
(290±26) km/s nella direzione (l,b)=(116,-59): (Vx,Vy,Vz)=(-65±22, 135±12,-249±6)km/s
Dispersione delle velocità:(σvx,σvy,σvz)=(63,33,17)km/s
Altri stream di materia oscura da Altri stream di materia oscura da galassie satelliti della Via Lattea galassie satelliti della Via Lattea
vicini al Sole?vicini al Sole?
Canis Major simulation:
Astro-ph/0311010 Ibata et al.
Posizione del Sole: (-8,0,0)kpc
.....molto probabile....
E’ ipotizzato che le galassie a spirale come la Via Lattea siformano per cattura delle vicinegalassie satelliti come la Sgr, Canis Major ecc…
... investigating halo substructures by underground exptthrough annual modulation
Possible contributions due to the tidal stream of Sagittarius Dwarf satellite (SagDEG) galaxy of Milky Way
EPJC47(2006)263
sunstream
spherical oblate
V8*
Vsph Vobl
V8* from 8 local stars: PRD71(2005)043516
simulations from Ap.J.619(2005)807
Examples of the effect of SagDEG tail on the phase of the signal annual modulation
5 10E (keVee)
180
160
140
120t 0
(day
)
mW=70 GeV
DAMA/NaI results:(2-6) keV t0 = (140±22) d
Ex. NaI:3 105 kg d
NFW spherical isotropic non-rotating, v0 = 220km/s, ρ0min+ 4% SagDEG
NFW spherical isotropic non-rotating, v0 = 220km/s, ρ0max + 4% SagDEG
Expected phase in the absence of streams t0 = 152.5 d (June 2nd)
Investigating the effect of Sagittarius Dwarf satellite galaxy(SagDEG) for WIMPs EPJC47 (2006) 263
sunstreamDAMA/NaI: seven annual cycles 107731 kg d for some SagDEG modelling
pure SI case
pure SD case:examples of slices of the 3-dim allowed volumeFew examples
green areas: no SagDEG
The higher sensitivity of DAMA/LIBRA will allow to more effectively investigate the presence and the contributions of streams in the galactic halo
Possible contributions due to the tidal stream of Sagittarius Dwarf satellite (SagDEG) galaxy of Milky Way
Constraining the SagDEG stream by DAMA/NaI - 2EPJC47(2006)263for different SagDEG velocity dispersions (20-40-60 km/s)
pure SI case
pure SD case
This analysis shows the possibility to investigate local halo features by annual modulation signature already at the level of sensitivity provided by DAMA/NaI, allowing to reach sensitivity to SagDEG density comparable with M/L evaluations.
The higher sensitivity of DAMA/LIBRA will allow to more effectively investigate the presence and the contributions of streams in the galactic halo
What about the indirect searches of DM particles in the space?
astro-ph/0211286
The EGRET Excess of Diffuse Galactic Gamma RaysIt was already noticed in 1997 that the EGRET data showed an excess of gamma ray fluxes for energies above 1 GeV in the galactic disk and for all sky directions.
EGRET data, W.de Boer, hep-ph/0508108
interpretation, evidence itself, derived mW and cross sections depend e.g. on bckg modeling, on DM spatial velocity distribution in the galactic halo, etc.
In next years new data from DAMA/LIBRA (direct detection) and from Agile, Glast, Ams2, Pamela, ... (indirect detections)
PLB536(2002)263
Hints from indirect searches are not in conflict with DAMA/NaI for the WIMP class candidate
... not only neutralino, but also e.g. ...
PLB536(2002)263... sneutrino, ...
... or neutrino of 4th familyhep-ph/0411093
Example of joint analysis of DAMA/NaI and positron/gamma’s excess in the space in the light of two DM particle components in the halo
in the given frameworks in the given frameworks
... or Kaluza-Klein DMPRD70(2004)115004
IJMPA21 (2006) 1445Another class of DM candidates:
light bosonic particles
The detection is based on the total conversion of the absorbed bosonic mass into electromagnetic radiation.
In these processes the target nuclear recoil is negligible and not involved in the detection process (i.e. signals from these candidates are lost in experiments
applying rejection procedures of the electromagnetic contribution)
Axion-like particles: similar phenomenology with ordinary matter as the axion, but significantly different values for mass and coupling constants allowed.
A wide literature is available and various candidate particles have been and can be considered.
A complete data analysis of the total 107731 kgxday exposure from DAMA/NaI has been performed for pseudoscalar (a) and scalar (h) candidates in some of the possible scenarios.
,h ,h h
a S0 S0,Sm S0,Sm
h S0,Sm S0 S0,Sm
Main processes involved in the detection:
They can account for the DAMA/NaI observed effect as well as candidates belonging to the WIMPs class
They can account for the DAMA/NaI observed effect as well as candidates belonging to the WIMPs class
Axioelectric contribution dominant in all “natural”cases → allowed region almost independent on the other fermion coupling values
Also this can account for the DAMA/NaI observed effect
Allowed multiAllowed multi--dimensional volume in the space defined by mdimensional volume in the space defined by maa and all coupling and all coupling constants to charged fermions (3constants to charged fermions (3σσ C.L.) in the given frameworksC.L.) in the given frameworks
only electron coupling
cosmological interest:at least below
Analysis of 107731 kg day exposure from DAMA/NaI.
Maximum allowed photon coupling
UHECR - PRD64(2001)096005
033 949
1≈⎥
⎦
⎤⎢⎣
⎡++≈
u
uua
d
dda
e
eeaa m
gmg
mgg
πα
γγ
Majoron as in PLB99(1981)411; coupling to photons vanish at first order:
⎟⎟⎠
⎞⎜⎜⎝
⎛−==
u
uua
d
dda
e
eea
mg
mg
mg
coupling model
The The pseudoscalarpseudoscalar casecase
Di Lella, ZioutasAP19(2003)145
IJMPA21 (2006) 1445
1) electron coupling does not provide modulation2) from measured rate: ghee < 3 10-16 to 10-14 for mh ≈ 0.5 to 10 keV3) coupling only to hadronic matter: allowed region in vs. mh
(3σ C.L.)NNh
g
Allowed multiAllowed multi--dimensional volume in the space defined by mdimensional volume in the space defined by mhh and all the coupling and all the coupling constants to charged fermions (3constants to charged fermions (3σσ C.L.) in the given frameworksC.L.) in the given frameworks
Also this can account for the DAMA/NaI observed effect
h configurations of cosmological interest in plane
DAMA/NaI allowed region in the considered framework.
• Allowed by DAMA/NaI (for mh > 0.3 keV )• τh > 15 Gy (lifetime of cosmological interest)• mu = 3.0 ± 1.5 MeV md = 6.0 ± 2.0 MeV
Many other configurations of cosmological interest Many other configurations of cosmological interest are possible depending on the values of the are possible depending on the values of the couplings to other quarks and to gluonscouplings to other quarks and to gluons……..
•• Annual modulation signature present for a scalar Annual modulation signature present for a scalar particle with pure coupling to hadronic matter particle with pure coupling to hadronic matter (possible gluon coupling at tree level?).(possible gluon coupling at tree level?).
•• ComptonCompton--like to nucleus conversion is the dominant like to nucleus conversion is the dominant process for particle with cosmological lifetime. process for particle with cosmological lifetime.
ghuu vs ghdd
( ) ( )ddhuuhddhuuhNNh ggAZggg −++= 2
If all the couplings to quarks of the same order: lifetime dominated by uand d loops:
⎥⎦
⎤⎢⎣
⎡+−≈−≈ ∑
d
ddh
u
uuh
q q
qqhqh m
gmg
mgQ
g 91
942
232
πα
πα
γγ
The scalar caseThe scalar caseIJMPA21(2006)1445
FAQ:FAQ:... DAMA/NaI ... DAMA/NaI ““excludedexcluded”” by CDMSby CDMS--II (and others)?II (and others)?
OBVIOUSLY NOThey give a single model dependent result using natGe targetDAMA/NaI gives a model independent result using 23Na and 127I targets
Even assuming their expt. results as they give them …
No direct model
independent
comparison possible
•In general? OBVIOUSLY NOThe results are fully “decoupled” either because of the different sensitivities to the various kinds of candidates, interactions and particle mass, or simply taking into account the large uncertainties in the astrophysical (realistic and consistent halo models, presence of non-thermalized components, particle velocity distribution, particle density in the halo, ...), nuclear (scaling laws, FFs, SF) and particle physics assumptions and in all the instrumental quantities (quenching factors, energy resolution, efficiency, ...) and theor. parameters.
•At least in the purely SI coupling they only consider? OBVIOUSLY NO
still room for compatibility either at low DM particle mass or simply accounting for the large uncertainties in the astrophysical, nuclear and particle physics assumptions and in all the expt. and theor. parameters.
Case of DM particle scatterings on target-nuclei
Case of bosonic candidate (full conversion into electromagnetic radiation)•These candidates are lost by these expts. OBVIOUSLY NO
(see also in Riv. N. Cim. 26 n. 1(2003)1-73 and IJMPD13(2004)2127, several papers in literature, astro-ph/0511262)
As a result of a second generation R&D for more radiopure NaI(Tl) by exploiting new chemical/physical radiopurification techniques
(all operations involving crystals and PMTs - including photos - in HP Nitrogen atmosphere)
The new DAMA/LIBRA set-up ~250 kg NaI(Tl)(Large sodium Iodide Bulk for RAre processes)
The new DAMA/LIBRALIBRA set-up ~250 kg ~250 kg NaI(TlNaI(Tl))(Large sodium Iodide Bulk for RAre processes)
etching staff at workin clean room
PMT+HV divider
Cu etching with super- and ultra-
pure HCl solutions, dried and sealed in
HP N2
improving installationand environment
storing new crystals
detectors during installation; in the central and right up
detectors the new shaped Cu shield surrounding light guides (acting also as optical windows)
and PMTs was not yet applied
view at end of detectors’installation in the Cu box
closing the Cu boxhousing the detectors
(all operations involving crystals and PMTs -including photos- in HP N2 atmosphere)
installing DAMA/LIBRA detectors
filling the inner Cu box with further shield
assembling a DAMA/ LIBRA detectorDAMA/LIBRA in data taking since March 2003,waiting for a larger exposure than DAMA/NaI
Some infos about DAMA/LIBRA data acquisition
DAMA/LIBRA in operation since March 2003
e.g. up to March 2006: exposure: of order of 105 kg x doverall sources’ data: of order of 4 x 107 events
Few examples of operational features (here from March 2003 to August 2005):
%4.7)60( =keVEσ
241241Am routine Am routine calibrationscalibrations((allall the the detectorsdetectors togethertogether))
E (keV)
tdcaltdcaltdcal −
freq
uenc
y
σ=0.4%
StabilityStability of the of the lowlow energyenergycalibrationcalibration factorsfactors
ratio of the peaks’ positions
2≈α
σ=0.9%
HE
HEHE
fff −
freq
uenc
y
StabilityStability of the high of the high energyenergy calibrationcalibration
factorsfactors
Perspectives of DAMA/LIBRAPerspectives of DAMA/LIBRAModel independent approach: Model independent approach: reachable C.L. as function of running time and of the low energy bckg rate. The shaded regions account for several model frameworks.
e.g., role of the increase of statistics and of the improvement in the bckg rate to identify a SI/SD coupled WIMP candidate in a particular given model framework of the many possible
• Allowed regions evaluated by simulating the response of the ~250 kg NaI(Tl) set-up to a WIMP having mW=60GeV, σSI=10-6 pb, σSD=0.8 pb and θ=2.435rad.
• Various exposure times are considered (from 1 to 5y).• In each panel different bckg rate.
More complete scenarios would be investigated and several uncertainties accounted for (see e.g. Riv.N.Cim.26n.1(2003)1-73)
Assumptions:
• 1σ C.L.• v0=220km/s,
fixed params• isothermal
spherical halo• etc.
Example of corollary model dependent quests for the candidate particle in a single simplified model/analysis framework:
…… other astrophysical scenarios?other astrophysical scenarios?Possible non-thermalized multicomponent galactic halo? In the galactic halo, fluxes of Dark Matter particles with dispersion velocity relatively low are expected :
sunstream
OtherOther darkdark matter stream frommatter stream from satellitesatellite galaxygalaxyofof MilkyMilky WayWay close toclose to thethe SunSun??
.....very likely....Can be guess that spiral galaxy like Milky Way have been formed capturing close satellite galaxy as Sgr, Canis Major, ecc…
Canis Major simulation: astro-ph/0311010
Position of the Sun: (-8,0,0) kpc
Effect on the phase ofannual modulation
signature?
Effect on |Sm/So| respect to “usually”
adopted halo models?
Interesting scenarios for DAMA
Possible contribution due to the tidal stream of Sagittarius Dwarf satellite galaxy of Milky Way
K.Freese et al. astro-ph/0309279
Possible presence of caustic rings
⇒ streams of Dark Matter particles
Fu-Sin Ling et al. astro-ph/0405231
An example of possible signature for the An example of possible signature for the presence of streams in the Galactic halopresence of streams in the Galactic halo
The effect of the streams on the phase depends on the galactic halo model
Phas
e(d
ay o
f max
imum
)
E (keVee)
Expected phase in the absence of streams t0 = 152.5 d (2nd June)
NFW spherical isotropic non-rotating, v0=220km/s, ρ0 max + 4% Sgr
Evans’log axisymmetric non-rotating,v0=220km/s, Rc= 5kpc, ρ0 max + 4% Sgr
The higher The higher sensitivity sensitivity ofof DAMA/LIBRADAMA/LIBRAwill allow to more effectively investigate will allow to more effectively investigate the presence or contributions of the presence or contributions of streamsstreams
in the in the galactic halogalactic haloDAMA/NaI results:(2-6) keV t0 = (140 ± 22) d
Example, NaI: 3 105 kg d
ConclusionsConclusionsDark Matter investigation is a crucial challenge in the incomingDark Matter investigation is a crucial challenge in the incoming years for years for cosmology and for physics beyond the standard modelcosmology and for physics beyond the standard model
DAMA/NaI data show aDAMA/NaI data show a 6.36.3σσ C.L. model independent evidenceC.L. model independent evidence for the for the presence of a Dark Matter particle component in the galactic halpresence of a Dark Matter particle component in the galactic haloo
Corollary model dependent quest for the candidate particle:• WIMP particles with mw~ (few GeV to TeV) with coupling pure SI or pure SD or
mixed SI/SD as well as particles with preferred inelastic scattering (Riv.N.Cim. 26 n.1. (2003) 1-73, IJMPD 13 (2004) 2127)
• several other particles suggested in literature by various authors(see literature)
• bosonic particles with ma~ keV having pseudoscalar, scalar coupling(IJMPA21(2006)1445)
• halo substructures (SagDEG) effects (EPJC 47 (2006) 263)• and more in progress...
The presently runningThe presently running DAMA/LIBRADAMA/LIBRA will allow to further increase the C.L. will allow to further increase the C.L. of the model independent result, to restrict the nature of the cof the model independent result, to restrict the nature of the candidate andidate and to investigate the phase space structure of the dark haloand to investigate the phase space structure of the dark halo
+ a new R&D towards a possible ton set-up we proposed in 1996 in progress... wait for more in the near future