DEAR DEAR eXperimenteXperiment

DDAANE NE EEXOTIC XOTIC AATOMS TOMS RRESEARCHESEARCH

LNF SPRING SCHOOL “Bruno Touschek”In Nuclear, Subnuclear and Astroparticle Physics

M.Iliescu, May 22, 2003 Frascati (Italy)

M. Augsburgerj, G. Beerb, S.Biancoc, A.M. Bragadireanuc,i,M. Bregantd, W.H. Breunlicha, M. Cargnellia, D. Chatellardj,J.-P. Eggerk, F.L. Fabbric, B. Gartnera, C. Guaraldoc, R.S. Hayanof,M. Iliescuc,i, T. Ishiwatarie, K.Itahashie, T.M. Itol, M. Iwasakie,R. Kinga, P. Knowlesj, T. Koikeh, B. Laussc,a, V. Lucherinic, L. Ludhovaa, J. Martona, E. Milottid, F. Mulhauserj, S.N. Nakamurag,C. Petrascuc,i, T. Pontai, A.C. Sandersonb, L.A. Schallerj, L. Schellenbergj, H. Schneuwlyj, R. Sekil,m, D. Sirghic,i, F. Sirghic,i D. Tomonoe, T. Yoneyamae, E. Zavattinid, J. Zmeskala

a Institute for Medium Energy Physics, Austrian Academy of Sciences, Austria b Univ. of Victoria, Dept. of Physics and Astronomy, Canada c Laboratori Nazionali di Frascati dell'INFN, Italy d Univ. degli Studi di Trieste, Dip. di Fisica and INFN Sezione di Trieste, Italy e Tokyo Institute of Technology, Japan f Univ. of Tokyo, Dept. of. Physics, Japan g Inst. of Physical and Chemical Research (RIKEN), Japan h KEK, High Energy Accelerator Research Organization, Japan i Inst. of Physics and Nuclear Engineering - " Horia Hulubei ", Romania j Univ. de Fribourg, Inst. de Physique, Switzerland k Univ. de Neuchâtel, Inst. de Physique, Switzerland l W.K.Kellogg Radiation Laboratory, California m Department of Physics and Astrophysics, California State University

The DEAR Collaboration The DEAR Collaboration

The determination of the isospin dependent KN scattering lengths through a few percent measurement of the shift and the width of the K line of kaonic hydrogen and the first measurement of kaonic deuterium

dKdKdK

pKpKpK

aaai

aaai

)fm eV (60122

)fm eV (41222

1-23

1-23

)3(4

1)(

2

1

C + 2/

2

)(2

1

10)0(

)0(

10

aaaaa

amm

mma

aaa

nKpK

kN

kNdK

pK

(Deser - Trueman)

The objective of DEARThe objective of DEAR

pdduup

psspy

2

1 '

4

N

KN

smm

my

A measurement of KN scattering lengths at the percent level would enable the determination of the KN sigma terms with a precision

of about 20% or less, to be compared with the 70% uncertainty of the present estimates.

Sigma terms are directly connected with the chiral symmetry breaking part of the strong interaction Hamiltonian.

Also, the fraction of strangeness content in proton

can be derived with better accuracy from KN and N sigma terms (Jaffe ‘87)

The implications of DEAR resultsThe implications of DEAR results

Kaonic Hydrogen cascade

}

n

4

3

2

1

s p d f

KkeVK

Strong Interaction causes:

energy shift compared to pure Coulomb

interaction

level width due to the short lifetime caused by Kaon capture

What DEAR measuresWhat DEAR measures

CCD-55 detectors positioning in the cryogenic setup

CCD-55 detectors positioning in the cryogenic setup

e-e+

K+

IPD2

D1

D7

D8

A1

A2

A3

A4

A5

A6

A7

A8

D3

D4

D6

D5

K-

Charge-Coupled Devices are solid state detectors with a pixel structure. They are excellent detectors for soft X rays in the high background environment of a collider, for the powerful rejection capability (given by the topology of X-ray events -single pixels-), together with a very good energy resolution, high efficiency and large active area.

Background suppression by single pixel selection

X-ray

Chargedparticle

Active depletion (30m)Substrate

How DEAR measures KH transitions: X-ray spectroscopic CCDsHow DEAR measures KH transitions: X-ray spectroscopic CCDs

Target and cryogenic

setup layout

Target and cryogenic

setup layout

Operating conditions:

20 K, 3 bar (~40 bar NTP)

Fiber-glass reinforced kapton targetFiber-glass reinforced kapton target

Requirements: high compaction to allow optimal shielding and light materials to reduce Bremsstrahlung

- fiberglass frames- cooling system mounted on the top- thin Al cold finger - reduced diameter of the socket group and, consequently, of the vacuum chamber

CCD mounting,cryogenics andon-cell electronics

CCD mounting,cryogenics andon-cell electronics

Pb walls

Pb platform

Vacuum jacket shielding

Overall shielding factor of the DEAR interaction region ~ 100

Target

e+ e-

Interaction point

Pb collimators

DEAR shieldingDEAR shielding

-Resolution and L.N. characteristics:thermal noise FWHM of about 15 eVenergy resolution at 5.9 keV (Mn K line) 136 eV, charge transport correction not applied

-Linearity: ~ 10-4

-Instability: below 4 eV/month -Charge transport inefficiency: ~10-6

-Synchronous readout of 16 large area detectors (CCD55-30)-Data flow 3264 MB/sec-Dual bus real-time system equipped with N.I. boards-Injection synchronization-Software dual slope integration

CCD55 new DAQ new amp Mn KK136 eV FWHM

0

500

1000

1500

2000

2500

0 200 400 600 800 1000

Channels

Cou

nts

DAQ performanceDAQ performance

-500 50000

200

400

600

800

1000

Shift (eV) [

Wid

th (

eV)

[

Dav

ies

et a

l, 19

79

Izyc

ki e

t al,

1980

Bir

d et

al,

1983

Constant Scattering LengthK-MatrixPotential ModelCloudy Bag ModelConsituent Quark Model

Iwas

aki e

t al,

1997

KpX

DEARpreliminary

result

State of art of

Kaonic Hydrogen

measurement

and

theoretical

predictions