. /c-,:.

Results from PESY-Heidel ber'~ Nai Lead Glass D!lt~c;tpr · ,•,-

·-.... ·

..... ,

by '

' . - : ,-.,:,-;.

.,•'

::0.·,1:,

w. Bartel, p, ·Dittmann, P. Duirker, J. Olsson, L O'f'!eitl,. I ( '

·. D. Pa11doulas,, ,p. Steffen .,.

·-. ,' r,; ' ' .,,, .

lL' frl.~scber. J. H·eintze, G. Heinzelmann, R. D. Heuer, R; Mti.ncJ~i:ll(~.·: ·· ' H. R.i eseberg ,, A. Wagner ''

. PhyfiikaUsahes Institut der Universiti:tt Heide'lib'el{r:J

'iJ

)_ ·,

· .. ,

N OTKESTRASSE 85 2 HAMBURG'o2 . -' ; . } . :~- - '• : ..

To be sure that your preprints are promptly included in the

HIGH ENERGY PHYSICS INDEX,

send them to the following address ( if possible by air mail ) :

DESY Bibliothek 2 Hamburg 52 Notkestieg 1 Gennany

RESULTS FROM DESY-IIEIDELBERG Nal LEAD GLASS DETECTOR

W. Bartel, P. Dittmann, P. Duinker* , J. Olsson, 1. O'Neill, D. Pandoulas, P. Steffen

Deutsches Elektronen-Synchrotron D-2000 llatnburg 52, Notkestrasse

Germany

DESY 85

•• U. Fritscher, J. Heintze, G. 1\einzelmann, R.D. Heuer, R. Munclhenke

H. Rieseberg, A. Wagner Physikalisches Institut der UniversitUt Heidelberg

D-6900 Heidelberg I, Philosophenweg 12, Germany

presented by J. Olsson

ABSTRACT

Results of a search for the decays J/ljJ ..,. rnc ..,. YYP0

and

J/ljJ + yn + 3y are presented. Preliminary results on $ 1 decays obtained in

a high s~atistics measurement are also presented. They include results of

a search for ljJ 1 decays involving the nc. The cascade decays

ljJ 1 + YX + yyJ/IjJ are clearly seen for PC(3.51) and x(3.55). An enhancement

of two standard deviations significance is observed for the decay

ljJ' _,. YX(3,41) -+- yyJ/IjJ, For these three decays branching ratios are given.

For the decay~,_,. yx(3.45) ..,. yyJ/1/J, an upper limit for the branching

ratio is given.

*Now at NIKHEF, Amsterdam

•• Now at IDAS GmbH., Limburg

-2-

INTRODUCTION

The DESY-Heidelberg collaboration has studied e + e- .1nnihilation at

the storn~e rings DORIS with a nonmagnetic. detector, In the first running

period, in 1975, data 1.-1ere taken mainly at the J/"<l' resonance and some

results from these measurements are presented in this report. A second

set of me<1surcments, in 1977~ was taken with a modified apparatus, It in­

cludes I 100 nb·l at the ijJ 1 resonance. Preliminary results from these data

are also presented.

a/ b/ c/ d/

The topics to be covered are

Apparatus description. Search for the decays J/ij; -)- Yll + yyp

0 and J/ljJ + Yll + 3y.

Search for 1/J' decays involvingcthe n . c

Cascade decays of ljJ 1 , c

APPARATUS

The details of the appara(YJ of the DESY-Heidelberg collaboration

have been described elsewhere and only the modifications made for the

1977 measurements will be described here. A section of the apparatus

transverse to the beam is shown in fig. Ia and an exploded view of the

energy counters is given in fig.lb.

In the inner detector (ID), the mercury converter has been removed,

while the three cylindrical drift chambers (CD) and the two scintillation

counter hodoscopes (H) have been left unchanged. In order to convert

photons and simultaneously measure the energy loss in the converter, an

active converter hodoscope (AC) has been installed. It consists of 28

Nat rod counters of 45 em length and 1.8 X0 (4.6 em) thickness. Photon

conversions are registered by the double drift chambers {CC) and the

scintillation counter hodoscopes (CH) behind the converter. The solid

angle covered by the active converter system is 19 % of 4~.

The Nat and unmodified. They converter.

lead glass counters behind the active converter were left

have a total thickness of 15.2 X0

, including the active

The lead glass system in the top and bottom regions of the apparatus

has been modified in order to improve the granularity and energy

resolution. 54 rectangular lead glass counters of 12.7 X thickness form

the top-bottom parts of the system. In addition, 32 prof~led lead glass

counters cover the gaps between sidewalls and top-bottom parts. In front

of this counter arrangement, a lead converter (CV) has been placed

between the second and third drift chamber of the inner detector. It is

tapered in such a way that particles coming from the interaction point see

a thickness of I X . 0

In the preliminary analysis presented here, an energy resolution

of 13 %/IE {F~~) is obtained for the ~ctivc converter and sidewall

counters. _In the lead glass top-bottom system, the energy resolutiou

is 13 %//E (FWUM). For photons converted in the lead, the resolution

is slightly degraded.

- 3 -

OE;Sy

26799

a

b

OESY Wf11-1GmKnaut

Fig.J a/ View of the apparatus transverse to the beam. b/ Exploded view of the energy counters.

- 4 -

The inner detector and the enerey counters both covt:r a solid angle of 86 h of 41T. Tn addition, part_icle detention is extended lo 95 % of 411 by two small angle hodoscopes ( 1) (not seen in fig. I) in front of which I X

0 of lead has bE'en placed.

The angular resolutions of the various components of the apparatus are sununarized in table I.

The trigger consists of several combinations of charged track multi­plicities and a certain minimum total deposited energy, as described in Ref (I), The solid angle for triggering is 86 % of lm.

Together with the outer hodoscope in the inner detector, the scintillation counters (CS} behind the energy counters can be used to reject cosmic ray events, by a TOF measurement.

Finally, a new muon detector, consisting of 114 chambers (MC) with 15 em wide drift spaces, extends the solid angle for muon detection to 60% of 411". The iron filter is 30 em thick. Together with the energy counters, it forms a hadron absorber of 4.6 interaction lengths.

SEARCH FOR TilE DECAY Jfl/! -1- Y'\

In this section, results are presented from measurements taken in 1975 with th~ apparatus before modifications,

In the search for the decay J/W ~ y~ , two possible decay modls of n have been considered, namely n -1- ypO ~nd n + yy. n is the I s

0 cfiarmonium state of even C-parity; which is ex~ected tochave a mass somewhat below the J/W mass.

0 JfW +me + YYP

The decay mode

J/W + ync . /, ypo

I + -<,." "

( I )

results in a final state of 1f+n-yy. In this topology, the decays

J/W + p1r ( 2 )

and

J/lj! -)- Yll' ( 3 )

can also be seen. ~ YP0

- 5 -

The sdection of 2 prong, 2 photon events has been described pre­

viously (I),_ in connection with the analysis of the decays _(2) and (1).

Using the measured directions of the charged particles (>-.'hich arc

assumed to be pions) and of the converted photons, the moJHenta are kine­

matically reconstructed.

The 1r+1r-y mass distribution, with 2 entries/event, is sho\<'n in fi5.2.

The hatched distribution is obtained \<•hen ffin+n- is restricted to the p

mass region ( .55 < mn+n- < 1.00 GeV) and myy is restricted to be outside

the no mass region (myy > .35 GeV). The latter restriction serves to

exclude events from reaction (2)o

A clear n' peak is seen, corresponding to the decay (3). The high

mass reflection of this peak is shown by the dotted line.

Fig. 2

J/<ji-Tt+Tf y y M{Tt+rt-y) 2entries/ennl

!ill [.55< M,•,- < 1.00 GoY] [Myy > .35 GoY]

Mass distribution of the 1f+-rr-y syston in t!"Je

re.a.::.tion J/Tp -~ 1f + 1T-yy.

- 6 -

Thexe is no indication of a n_at·rov.• high mass sUite, which Hould correspo<.d to r.c<lctio!l (J), Tn th0 milS!! }-actge 2.5 < mnc < 2,9 GcV,

an 11pper 1 imit for the -::ombined branching ratio L; obtained,

BR (J/IjJ + Yll ) o BR (n -r yp 0 ) < 2,6 o 10-4 c c

(90 % C.L.).

J/lV -+ Ync -+ 3y

The decay JN ··r YJl

( yy ( 4)

has a thrGe photon final state. The selection criteria for these events

have been described earlier (2). The events are reconstructed using the

measured positions of the three conversion points and the beam line. The

momenta of the three photons as well as the location of the interaction

point along the beam line (z-vertex) are then calculated. The distrib­

ution of the reconstructed z-vertices is shown in fig.3. It agrees with

the distribution obtained from the reconstruction of events with charged

tracks. To obtain the final sample of 78 events, a cut was made in the

z-distribution at .± 25 nm1, as indicated by arrows in fig.3. It was

further checked that the calculated and measured photon energies agreed

within the resolution.

E e+e--yyy E 30

0 ~

---~20

Fig. 3

mm

Distribution of reconstructed interaction points along the beam axis in the reaction e+e- _, 3y at!';"' 3.! GeV.

- 7 -

Each event gives three diff01e.1t m<1sses m-yy for the 2) pairs, The Dnlitz plot of fig.4 shmn, the lmV"est m\Y vs. the highest m2 , with I entry/event. A clear n signal is seen and a few events yy appear in the n' band, corresponding to the decays

J/lp -}- rn 4 yy ( 5 )

J/!j! -)- Yll'

" yy ( 6 )

This is also seen in the low mass projection of fig. Sa. The decays (5) and (6) were discussed in (2)

Fig. Sb shows the projection of the highest myy• Events with the lowest myy in the n mass region ( .45 < n~y < .65 GeV) have been omitted,

Several reactions can contribute to the histogram in fig,5b. Besides reaction (4), there is a reflection from reaction (6). Furthermore, there are contributions from the QED process

+ -e e + 3y ( 7 )

as well as multiphotOn final states (2) with only three photons observed in the detector. The reaction

J/~ + y~o~o ( 8 )

is expected to be the most important source of this background.

The contributions from reactions (6) and (7) can be calculated and are shown in fig.Sb. The possible contribution from multiphoton final states has been studied in two ways :

a/ In events with 4 observed photons, the lowest energy photon was neglected and the events were treated in the same way as real three photon events,

b/ The decay (8) was generated by Monte Carlo methods and events with only three photons observed in the appa­ratus were treated as ·real three photon events.

Both methods reveal that neither the z-vertex distribution, nor the comparison between calculated and measured photon enetgies, allow such events to be distinguished from genuine three photon events. Background contribution from multiphoton final states can therefore not be excluded by these means.

The size. of this contribution was estimated from the observed number of events with more than three photons in the final state, as well as from the branching ratio of the decay J/ij; _.,. yf (3)

- 8 -

n1e co1'clusion i:-, thc,t most of the events in the .hroad en1wncC'r,lent above background in fig. Sb could be due to multiphoton final sta.tes.

m[ [GcV~

,. . • ,\-----.

e•e- -YYY 78 accepted events fs=J_lGeV

..

0 •••

Fig. 4

4 I 6 7 8 m~ [GeV1J~g--

1B ll' 1.0 1.1 11 13 14 1' 1fi 17 18 1l 30 mH [GeV]

Dalitz plot for the reaction e+e--+ 3y at f;"' 3.1 GeV;

lowest ~y vs •. highest ~Y' I entry/event.

The expected mass resolution at 2~ 7 GeV is 80 MeV. There is in fig.5b no significant indication of the presence of the decay (4) of-J/ij;. into a narrow, heavy state nc· In the maSs range 2.6 < m~ < 2.85 GeV, an upper limit is obtained for the combined branching ratlo,

BR (J/ij;-+ yn ) • BR (n -+ yy) < 3.2 • 10-4

c c (90 '7. C.L.)

The hatched distribution in fig. Sb shows the part of the sample that was obtained in the first measurement period in 1975. Together with data from the DASP collaboration the excess of events above background was then taken as an indication of the possible existence of a heavy mass state in the region 2.7- 2.8 GcV (4). Increasing the statistics in our experiment by more than a factor of tHo did not improve the signal, how­ever. In their full sample, the DASP collaboration observe a narrow state X at /..83 GeV (5) uith a branching ratio of 1,4 • 10-4. This value corresponds to 5-6 events in our sample and is consistent with the data.

- 9 -

~ f- ~ ;.;-~-::v-~3i'c;; :0 ~ 15 n· ?CCE'plcd evc1 <iS ClD ~

E 101 I 0 ... OJ .0 E :; z

Fig. 5

5

0

>10 "' ::;:

0 S2

05 l.O . M(yy)Low

1.5 [GeVl

f/e--yyy accepte>devents Ys=3.1G0V (~-band excluded)

[2] 151 Runperiod

-t) t-OED ~ --- y~' "' 0 ~

"'

a

Ef I rl'i:i.:W.ll 1b ::> z

h J JLt~.~~~~xi~>~q . m , 1 Q .. i ~--:,)-;-:·t-X>•::;>'"<·?-:<_.(-;;<.-:-:; -',;X-~· r:i•.

2.0 2.5 M(yy)high

3.0 GeV

a/ Mass distribut:i_on of lowest n~.yy in the reaction e + e- + 1y

at IS"' 3.1 GeV.

b/ Hass distribution of hirhest myy in the reaction e+e- -~ 3y

at fS, 3.1 GeV.

- 10 -

~:EARCH FOR ~,' DECAYS INVOLVING TllE nc

In this and the foll01dn~ section, preliminary results from a high

statistics mcasurCFJCt~t cf 1./!' decays in 1977 are presented. The measure­

ments \H~re performed with the modified Dpptlratus described above,

Since an absolute normalisation is not yet available, all branching

ratios <Jnd upper limits are normalised to the decay

1'' .-+ n J/1)!

using the previously measured branching ratio of (4 .3 :f: .8)

this decay (6}.

(9)

-2 10 for

Several possible decay modes of ;J;' involving the state T)c are

shown below,

• ljJ'

~u C rtrf w v rtrf

ljJ'

(Y

~c-7~- v :J/l)J

~c

namely

- 11 -

.. ~ + -

Y1:1'

' 1., rr 11 nc

l~ yy

1/J' + Wll

~~c:Y_ o

l 'IT TI 1T

if!' + YTl 4.cypo

rpf + rn /.,.c

yy

( 10)

(II)

( 12)

(13)

·In reaction have a mass

(10), TJ' is the 2 1s0 somewhaE below the

charmonium state which is expected to W' mass.

+ - + -•P' -+ YTJ~-+ yrr 1r nc -+ n n 3y

The final state state resulting from

. -of this reaction is n n 3y. the well known decay chain

$' + n+n- J/W + n+n-3y.

This is also the final

(14)

where the reactions (4), (5) and (6) contribute, and a study of reaction (14) provides a check on the correctness of the event selection and re­construction methods.

Events with two charged tracks and three photons were selected, with the additional requirement that at least two photons have a measured energy higher than 800 MeV. These events were reconstructed by using the measured directions, the measured energies of at least twO of the photons and by assuming the pion mass for the charged particles. In order to study reaction (14), the mass of the three photons was in addition con­strained to be equal to the mass of J/W. In this way, a sample of 14 events was obtained.

In the same way as described abqve for J/lj.! decays into three photons, a Dalitz plot for the masses of the yy pairs is obtained. It is sho~n in fig.6, The contributions to this plot from the reactions (4)j (52 and (6) can be calculated from the measured branching ratios (I), (2 • ( ) and are :

W' + n+rr- . -7.5 ± J/W + u n rn 3 events . - . -w' -+ 11 11 JfW ->- n 11 YTJ' < I event

lj.! 1 -+ 11+n- J/lj.!-+ 1f+TI-yX(2,83) < I event

- 12 -

These numbers are consistent with Lh~ ,Jistribt!tlo:l in fie.6.

In order to study the 11~ production in (10), the 2 prong, 3 photon sample was again reconstructed usinp-, directions and meaf..ured photon energies. Instead of constraining the three photons to the J/ljJ mass, the mass of the t1~0 most ('nergctic photoas was now constrained to the mass of X(2.83), assuming this particle to be the llc• By this method, 7 events were found to fit. They are identical to the events marked .in fig.6 and can therefore mostly be attributed to reaction (lf+), with J/ljJ decaying into Yll·

m[ [GeV2]

3

1

4> 1 -rr'rf Jt4>-- Ttn:Jy

0 Events fitting

• • • •

7

ljJ'-- Y 1Jc LrrrfX(2.8l

l.yy

Fig. 6 Dalitz plot for the 3y system in the reaction lj.!' + n+n-J/lj.!-+ 3y.

The mass distribution of the lT+n-X system for the 7 events is shown in fig,7, No signal for reaction (10) is seen. Assuming the nt to be a narrow state in the mass range 3,2 < mn• < 3.65 GeV, an upper limit is obtained for the combined branching ratio,

+ - -5 BR (lj.!' ->- yn~) o BR (TJ~ ->- n n X) o BR (X+ yy) < 5.8 o 10 (90% C.L.)

- 13 -

No/50 MeV 1f I I 0 I I I 0 )• (GeV)

3.0 3.2 3.4 3.6 mrtrtX

Fig. 7 Mass distribution of the tr+Tr-X system in the decay ljl' -')- ' ync

4. tr\r X

The decay chain (10) has recently beefi discussed by Greco and KrammerP), who conclude that an observation pf the decay chain (\0)

with a combined branching ratio greater than 4 • Jo-5 would be in con­

tradiction to the standard c.harmonium model.

The upper limit obtained above also applies to the corresponding

decay chain via PC(3.51),

Using th~ measured

ra-tio of· the decay ratio

~· + yP

Lc

+ -n n X

4 yy

(S) value of (7.1 ± 1.9)

W' + yPC' an upper limit • 10-

2 for the bra~ching

for the combined branching

+- -4 BR (Pc(3.51) + lT 11 X) • BR (X-+ yy) < 8.3 • 10 (90 % ·c.L.)

can be calculated.

W' -+ wnc

The final state in reaction (I I) is two charged tracks and four

photons. Events with this topology were selected, again with the re­

quirement that at least two photons have en~rgies of more than 800 ~leV.

These events were reconstructed by using the measured directions of the

particles, at least two of the measured photon energies and by assuming

the charged particles to be pions. In adCition, the mass of the tYJO lowest

energy photOns was constrained to be eql.!a,l to the mass of the rr 0 and the

mass of the charged particles and the n° was constrained to the mass of

w(783).

- 14 -

Only two events were found to fit, with the mass of the two high high - .

en..:,rgy pl'tJlons lllyy "' 2,78 and 2,80 GeV. S1ncc the background has not

yet b_een studied, the two cvenls are used to put an upper limit on the

comhi.ned branching ratio for reaction {II), \olith the assumption that

nc has a mass around 2.8 GeV,

-4 BR (~' -+ wnc) • BR (n~-+ yy) < 2.3 • 10 (90 % C.L.)

An upper limit of 10-J was previously obtained from the 1975 data (g)

W' -)- YTJ -~ YYP0

c

The final state for reaction (12) is two charged particles and two

photons. Such events were selected with criteria similar to those -for

reaction ( !) and reconstructed by using the measured directions and by

assuming the charged pnrticles to be pions, With the addit-ional require­

ment that m11 +11 - be in the po region (.55 < m1T+11- < 1.00 GcV) and myy be

outside the no mass region (myy > . 35 GeV), only three events vere

found, with the mass m11 +11 -y in the range 2.5 -- 3.0 GeV, This leads to

an upper limit on the combined branching ratio

0 -4 BR(ijJ' + Y'\) • BR(nc -~ yp ) < 1.8 • 10 (90 % C.L.)

with 2,5 < m < 3.0 GeV. nc

The sample also gives an upper limit on the decay

W' + rn' I, ypo

( 15 )

with only one event found,

BR(l/! 1 -+ yn') < 2. 3 • 10 -4

(90 % C.!..)

This improves the upper limit of 1.1 • 10- 3 obtnined from the 1975 data(!).

1f!'-:-ync--+3y

The final state consists of three photons, as for reaction (4). Such

events were selected and reconstructed in the 52:'!'=' Y.'ay as dcscribC'd above

and in Rtof (2), by demanding three converte-d pilotcns. 1he rt·sulting

Dalitz plot is shown in fig. Sa and the corresponding high mess projec­

tion in fig, Sb. Th& rise of the di.strihutio11 to1.·ards hi~jher 1,asses

agrees witi1 tile exp~ctcd distribtJtion from til~ QfD prGce~£ (7). Ti1e s~all

excess of events in the mass region 2.7- 2.G GeV gives an upper limit

for the branching r<ltio of reaction (13),

-I, RR(i.)i' --+ Ync) • BR(ne ·• yy) < 5.0 • 10 (90 Z C.L.)

- 15 -

with the mass of llc in the range 2.7 < r.~r1 c < 2.R GeV, The DASP collabC'r-ation has obtained the limit 3,4 • JQ-11 for t!w decay l.ji' -~ yX(2.83), X + yy ( 10).

i-'e conclude that no signal corresponding to the state nc has been observed in this experiment so far. The upper limits obtained above are summat·ized in table II.

m~Y'l2 (Gev2

J

4.

8

3. 4

2.

. .. 1.

b/ No/50 MeV

Ll1 _,.

25 3.0 3.5 (GeV) mhigh

yy

a; .....

I . \ ··.:·:·=\\ ( high 2 2 6. 8. 10. 12. "'myy ) (GeV )

Fig. 8

2.5 2.9 3.3 3.7 m~1h (GeV)

a/ Dalitz plot for the reaction e+e- ~ 3y at.(;= 3.7 GeV.

b/ Mass distribution of highest myy•

- 16 -

CASCA!)E DEC!.YS 01:' 1jJ'

The radiative decays of i./J' intv J/~.ji via intermediate states of even C-pa ri ty,

-,---.-lj;'

~ can be studied in the final state topology of tHo photons and two charged particles, using the 2-body decay of J/lp into fl+\1-. In the sam!'. topology, the decay !jJ' + nJ/1./J can be observed, Although the decay J/lp + e+e-also contributes to the same topology, only the decay J/W -~ \1+\1- will be considered in the present study. 'l1le electrons are rejected by a cut on the pulseheight in the energy counters.

The ev€nts were reconstructed by using the directions of the four particles, with the &dditional mass constraint m

11+

11- = mJ/~· Events with

disagreement between fitted and seen photon energies were rejected.

The mass distribution of the two photons is shown in fig.9. A clear n signal is seen, corresponding to reaction (9). As mentioned above, the decay (9) is taken as a preliminary normalisation .

1be mass distribution of the yJ/~ system is plotted in fig.IO (only the high mass solution). Events with the two photon mass myy in the 1 mass region (myy > . 500 GeV) have been ami tted. Two peaks are clearly seen, corresponding to the states previously observed at 3.51 GeV (Pc), and 3.55 GeV (II). At the mass of 3.41 GeV, where a state has been ob­served (11), an enhancement of two standard deviations significance can be seen. In the region of 3.45 GeV no clear structure is seen. A state at this mass bas previously been reported (II).

A first estimate of the number of events belonging to the various states leads to the following branching ratios,

BR(W' ~ rx(3.41)) BR(x(3.41)-+ yJ/~Ji) '0 (0.2 ± 0.1) I0- 2

BR(W' ~ Yx(3.45)) BR(x(3.45) -+ yJ/IJ!) < 0.6 • 10 -2

(90 7. C.! .. )

BR(~Ji'-+ yPc(3.51)) 8R(Pc(3.51) + yJ/~)· (3.3 ± 0.8) lo- 2

BR($ 1 -+ Yx(3.SS)) BR(x(3.55) -~ yJ/1J..) • (2.3 ± 0.6) I0- 2

- 17 -

In calculating these estimates, fl backgrollr.d of 150 ~ SO events from

the decay if!' -* 1101r 0 J/'i;, with only two photons c:etected, has been subtracted.

No/5 MeV 60

l)J' - yy J/L\J

40 995 events

20

0 nrl o pcl!_1

__ ,__----,----,-- (GeV) ~-

J 2 3 ~ 5 .6 myy

Fig. 9 Mass distribution of the yy system ir. the decay 'P' ·) ·nJ/;J!

No/5 MeV T

50

40

30

20

10

- 18 -

~;-- yyJ/L\J

myy ~ .5 GeV

708 events

!!_> (GeV) ...___.,-1-3~.4~-3~.5~~3.6. mYJ/~>

Fig. 10 ~lnss distribution of the yJ/;J,J syc;tcm in the decay,~· -) '('(J/Tj;

Only the highest mass solution is plotted.

- 19 -

It is a plc.~surc to acknmvledge IJH' c;;:::ellcnt ;md effi d cnt- 'dark of the DOlUS machine group, of the DESY liallendienst and of tlw lk:idclberg physics institute 1vor!<shop. \Je thank K, B·.:tldcr, Dt, B. Gram::, P. Lcnnert, H. Matsunura and H.J. Seidel for their con~petent t·echnical aso;istance and for t·heir help in running the cxperim2nt. Furthcr;1:cre, the m£~lb('rs of thp !k,idelberg group thank the De~Y dil-cctoratc for their ·kind hospitality, This \VOrk was partly suppvrtcd by the Bundeshlini~::c,rlu:Jc fi.ir Forschung und Technologie.

I.

2.

3.

4.

5.

6.

7.

8.

9.

10.

II.

\,1, Bartel et al.,

W, Bartel ct: al.,

- 20 -

REFEEENCES

G. Knies, PL!TTO-collaboroltion,

J. Hcintzc,

w. Braunschweig et al.,

w. Tanenbaum et al.,

M. Greco and M. Krammer,

C.J. Biddick et al.,

R.D. Heuer,

w. Braunschweig et al.,

w. Braunschweig et al.,

G.J. Feldman et al.,

W. Tanenbaum et al.,

J.S. Whitaker et al.,

PL 6f1B, 483 (1976)

PI. _66B, 489 ( 1977)

Proceedings of the 8th Intern. SY!'lJl. on Lepton and Photon J.nteractions at Eigb Energies, Hamburg, Germany,

. 1977.

Proceedings of the 7th Intern. Symp. on Lepton and Photon Interctctions at High Energies, Stanford, USA, 1975 and Desy 75/34 (1975).

PL 67B, 243 ( 1977)

PRL ~. 402 (1976)

PL 69B, 313 (1977)

PRL 38, !324 ( 1977)

Thesis, Heidelberg 1977, (unpublished)

PL~, 2!19 (1977)

PL 57B, !107 (1975)

PRL 12_, 821 (1975)

PRL 12.• 1323 (1975)

PRL lZ_, !596 (1976)

- 21 -

TABLE I

Solid angle coverage and angular resolution of apparatus components.

Apparatus component and solid angle Angular resolution (FHHM)

Inner detector Charged tracks ,. , 4 rnrad

86 % of 4n 08 "' 30 mraU

Active converter Converted photons ,. , 70 mrad

and 6o ., 80 mrad

Sidewall counters 0'!! "" :U!O mrad 19 % of 4n Unconverted photops oe 100 mrad

Top-bottom Converted piuror_s ~ct; 7S w.cad

Lead glass counters 60 "' 65 mrad 67 % of 41T ,. , 80 mrad

Unconverted photons 60 45 mrad ---·------ --

TABLE II

Upper limits for decays of J/W and W' involving the state nc· All values are given with 90 % C.L.

BR(Jfili + yn,) • BR(nc + yp 0 )

BR(J/W + rnc) • BR(nc + yy)

BR(W' + yn~) • BR(n~ + n+n-X(2.83))

BR(X(2.83) + yy)

BR(Pc(3.51) + rr+n-X(2.83))

BR(X(2 .83)--+- n)

BR(tJI 1 + wnc) BR(De -)- yY)

BR(tJ!' -+ me) BR(nc + yp 0)

BR(tJ!' +ync) BR(nc + n)

BR(1J1 1 -)- Yn')

< 2.6 w-4

< 3.2 • w-4

< 5.8 10-5

< 8.3 Jo-t•

< 2.3 Jo-4

< I .8 10-4

< s.o 10-4

< 2.3 10-l.

(2 .5 < m11e < 2.9 GcV)

(2.6 < mne < 2.85 GeV)

(mne ~ 2.8 Ge'.J;

(2.5 < mflc 1.0 G0V)

(2.7 < mnc < 2.& tcV)