cπ−p interactions

Nuclear Physics B58 (1973) 77-92. North-Holland Publishing Company

CHARGED PARTICLE MULTIPLICITY DISTRIBUTIONS FOR

33.8 GeV/c K - p AND 50 GeV/c 7r-p INTERACTIONS

V.V. AMMOSOV 5, J.P. BATON 8, P. B E I L L I E R E 3 *, P. BOSETTI ], V.A. B U M A Z S H N O V 5, M. C Z E J T H E Y - B A R T H 3.*, D.P. D A L L M A N 9, A. D A U D I N 8, B. D E L E R 8, N.G. D E M I D O V 5, T.W. DOMBECK 6, P. D U I N K E R 4, P.F. E R M O L O V 5, A.B. F E N Y U K 5, P.A. G O R I C H E V 5, F. G R A R D 7, H. G R A S S L E R 1, S.A. G U M E N Y U K 5, Ph. H E R Q U E T 7, G. K E L L N E R 4, J. K E S T E M A N 7.*, E.P. K I S T E N E V 5, W. K I T T E L 4, V.M. K U B I K 5, D. K U H N 9, K. L A N I U S 2, J. L A U R E N T 7, A. M E Y E R 2, B.A. M A N Y U K O V 5, A.M. MOISEEV 5, D.R.O. M O R R I S O N 4, L. MOSCA 8, M. N E V E U 8, V.M. P E R E V O Z C H I K O V 5, R. POSE 2, J. S C H L E S I N G E R 7.*, R.M. S U L Y A E V 5, P.R. T H O R N T O N 6, F. T R I A N T I S 8, F. V E R B E U R E 3.*, A.P. V O R O B Y E V 5 and R. W l N D M O L D E R S 7. France

Soviet Union and C E R N - Soviet Union Collaborations

Received 6 March 1973 Abstract: Topological cross sections and average charge multiplicities {nc), are presented for 33.8 GeV/c K - p and 50 GeV/c 7r-p interactions observed in the 4.5 m Mirabelle hydrogen ,bubble chamber at Serpukhov. Values for (n c) of 5.16 -+ 0.08 and 5.71 +-0.13 were found for the K - p and ~r-p reactions, respectively. The two quantities (n c} and the correlation term f2 have been tabulated for 7t-+p, K+-p, and pp reactions at various energies. It is shown that the energy variation of each of these two quanlities is described by a universal curve when plotted against the Q-value of the reaction. The ratio (nc}/D, where D is the dispersion of the multiplicity distribution, is found to approach the constant value of 2 from above as the energy increases.

(1) Physikalisches Institut der Technischen Hochschule, Aachen. (2) Institut fiJr Hochenergiephysik der Akademie der Wissenschaften der DDR, Berlin, Zeuthen. (3) Interuniversitary Institute for High Energies, ULB-VUB, Brussels. (4) CERN, European Organization for Nuclear Research, Geneva. (5) I.H.E.P., Serpukhov. (6) Physics Department, Imperial College, London. (7) Facultd des Sciences, Universit~ de l'Etat, Mons, Belgium. (8) D.Ph.P.E., Saclay. (9) Institut fiJr Hochenergie Physik der (3sterreichischen Akademie der Wissenschaften, Vienna. * On leave of absence from Ecole Polytechnique. ** Chercheur ITSN, Belgique. *** Also at Universitaire lnstelling Antwerpen, Antwerp.

78

V.V. Ammosov et aL, K - p and n-p interactions

1. Introduction The results presented in this paper were obtained with the 4.5 m Mirabelle hydrogen bubble chamber at the Serpukhov accelerator. The fast ejected protons were directed on to an external target and 33.8 + 0.2 GeV/c K - mesons were obtained by a 2-stage RF separation [1 ]. In order to estimate the beam contamination some pictures were taken with the R F generator switched off. F r o m a count of the number of interactions and the number of tracks on those pictures, the beam contamination was found to consist of about 5% pions and 2% muons. Also counter measurements in the RF beam indicated that the muon contamination was very small. The p contamination is negligible at this energy according to the production curves. The 50 GeV/c 7r- experiment was performed with an unseparated beam of negative particles. The K - and p contaminations are smaller than 1% at this energy. The m o m e n t u m resolution at the m o m e n t u m slit is equal to 0.25%. A sample of 11 000 K pictures and 1 580 7r- pictures was scanned twice. The fiducial volume was 2.6 m long and located at the centre of the cylindrical bubble chamber of 4.5 m length and 1.6 m diameter. The events were examined on all of the 8 views in which they were observable. Beam tracks were counted on every frame at the entrance and at the exit of the fiducial volume. The differences between the two beam counts were checked to be equal to the number of events found in the fiducial region. This is particularly important in determining the zero-prong cross section. At the end of this procedure our scan efficiency was estimated to be better than 99% for all topologies except for 2 prongs where events with a short proton are lost. The results presented here are based on 5 842 K p events and 1 509 7r-p events. There were an average of 3.0 K - beam tracks per frame and 5.0 7r beam tracks per frame, respectively. One-prong events, mainly K decays, were not included. The sample of 3-prong events was corrected for the expected number of r-decays. The other events with an odd number of prongs ( < 1%) were assigned to the next even charged multiplicity or to the preceding one, according to the sign o f the charge balance (short protons and secondary interactions near the primary vertex, respectively). The results for K - p at 33.8 GeV/c and 7r p at 50 GeV/c are presented in sects. 2 and 3, respectively. The multiplicity distributions are then compared with various theoretical and empirical predictions in sect. 4. The question of energy dependence is discussed in sect. 5. Compilations of the variation o f cross section with energy for each multiplicity are presented. Results on the energy variation of (n c) and o f f 2 , where f2 = ( n c / n c - 1 ) ) - (nc)2, are discussed. Finally, the tendency of the ratio (nc)/D, where D is the dispersion of the multiplicity distributions, to approach a constant value at high energy is discussed in terms of a two-component model of high-energy interactions.

79

v. V. Ammosov et al., K - p and n - p interactions

2. Results on K - p interactions at 33.8 G e V / c Table 1 gives the n u m b e r o f events per t o p o l o g y and the topological cross sections for 33.8 G e V / c K p reactions. To obtain topological cross sections, it is necessary to correct for the loss o f short protons in t w o - p r o n g events. Measurements were made o f the protons f r o m 2-prong events w h i c h s t o p p e d in the chamber and an estimate was o b t a i n e d o f the t-value at which the loss o f short p r o t o n s was i m p o r t a n t . It was assumed that only elastic events are lost. Our sample o f events in the I tl-range 0.08 to 0.20 G e V 2 was normalized to the values o b t a i n e d f r o m c o u n t e r e x p e r i m e n t s [2] where the total elastic cross section is Oel = 2.5 -+ 0.3 mb and the slope b = 7.85 -+ 0.20 G e V -2. It was f o u n d

Table 1 K - p topological cross sections at 33.8 GeV/c Number of prongs

Number of events (uncorrected)

Number of events (corrected)

Cross section (rob)

0 2 2 elastic 2 inelastic 4 6 8 10 12 14 16

85 1416

1752 1481 764 267 65 10 2

85 1616 737 879 1752 148l 764 267 65 10 2

0.29 5.48 2.50 2.98 5.94 5.03 2.59 0.91 0.22 0.03 0.01

Total

5 842

6 042

20.5 -+ 0.1 a)

5 305

18.0 -+0.5

Total inelastic

-+ 9 -+ 73 -+ 88 a) ± 114 ± 42 ± 38 _+28 +_ 16 ±8 ±3 ±1

-+ 0.03 +- 0.25 -* 0.30 a) -+0.39 ± 0.14 ± 0.13 -+ 0.09 -+ 0.06 -+0.03 ± 0.0l ± 0.01

a) Input numbers, see text.

that 27 -+ 3% o f the elastic events are lost in the bubble c h a m b e r e x p e r i m e n t . The cross section derived f r o m the bubble chamber (by counting the n u m b e r o f b e a m tracks and interactions, correcting for the loss o f slow p r o t o n s and assuming negligible b e a m c o n t a m i n a t i o n s ) is consistent w i t h the value o f Oto t = 20.5 + 0.1 mb derived f r o m a c o u n t e r e x p e r i m e n t [3]. The average charged multiplicity for the inelastic reactions (including zero prong events), (nc) , is f o u n d to be

80

V.V. A m m o s o v et al., K - p and n - p interactions (n c) = 5.16 -+ 0.08,

and the dispersion, D, is D = (
3. Results on 7r- p reactions at 50 G e V / c T~ble 2 gives the n u m b e r of events per t o p o l o g y and the topological cross sections for 50~GeV/c n - p reactions. The\'loss of short protons in the 50 G e V / c n - p e x p e r i m e n t was estimated as for the K - p experinaent. The values taken f r o m c o u n t e r experiments w h i c h were used, are Oel = 3 . @ +- 0.12 mb [4],

slope, b = 8.5 + 0.2 G e V 2 [2].

t I

Table 2 / n - p top~ogical cross sections at 50 GeV/c 1 pNrUTi~ber ~/of Number of events (uncorrected)

Number of events (corrected)

Cross section (mb)

0 / 2 / 2elastic 2 inelastic 4/ 6 8 10 12 14 16

387 381 230 109 44 11 1

10+-3 421 -+ 35 216 +- 7a) 205 +- 35 387 +- 20 381 -+ 19 230+- 15 109+- 10 44 +, 7 11-+3 1 +- 1

0.2 6.4 3.3 3.1 5.9 5.8 3.5 1.6 0.7 0.2 0.02

Total

1509

1594

24.3 ±0.1 a)

1378

21.0 +- 0.9

10 336

Total inelastic

+-0.1 +- 0.5 +-0.1a) +- 0.5 +- 0.3 +- 0.2 +-0.2 +,0.2 +, 0.1 +-0.1 +, 0.02

a) Input numbers, see text.

The percentage o f elastic events lost because o f the short range o f the p r o t o n recoil was 34 +- 5%. By c o m p a r i n g the total cross section derived w i t h the value o f Oto t = 24.30 -+ 0.08 mb f o u n d f r o m a counter e x p e r i m e n t [3], the m u o n contamination o f the b e a m was found to be negligible (3 -+ 3%).

81

K V. A m m o s o v et al., K - p and n p interactions

The values of the average charged multiplicity and the dispersion are found to be (n c ) = 5 . 7 1 + 0 . 1 3 ,

D =2.72+-0.06.

4. Discussion of multiplicity distributions We consider the multiplicity distributions of the K - p and n - p experiments. The resemblance of the multiplicity distribution to a Poisson distribution has been noted at low energies [5] and some theoretical models have predicted Poisson distributions. However, in figs. 1 and 2, our results are shown to be inconsistent with a Poisson distribution as has been observed in high-energy pp interactions [6]. Wang [7] has proposed two models which give predictions of multiplicity distributions. These two models are compared with the data in figs. 1 and 2. It can be seen that Wang II is inconsistent with the data; and while Wang I gives a better overall fit, the probability is low for K p interactions.

I

/e - \ iI

,

I

I

I

K'p at 33.8 GeV/c ~

\

IZ

_ _ Poisson

X./N = 2 4 l l

_,_Wang I

X~N =70/7

___Wang 11" X2/N =348/7 w

1511,0

m

z

1000

O

-

0

2

4

6

8

10

12

"

14

16

nc

Fig. 1. Comparison of charged particle multiplicities in K p reactions at 33.8 GeV/c with a Poisson distribution and with the Wang 1 and Wang II models.

82

V.V. A m m o s o v et al., K p and ~r-p interactions I

t

I

W-P

i

at

I

I

I

50 GeV/c

I

/f-~

~ __Poi.on ×'/N~ 32/7

l//

~ It

lZ b4

_._Wang I X-2/N.

71 7

'\ \lI

l

Z

10C

0

I 2

\'~.,, 6

8

10

12

14

16

nc Fig. 2. Comparison o f charged particle multiplicities in I r - p reactions at 50 GeV/c with a Poisson distribution and with the Wang I and Wang I1 models.

Czy2ewski and Rybicki [8] have proposed an empirical fit to multiplicity distributions which works well over the range from 4 to 69 GeV/c with 7r-+pand pp reactions. They proposed plotting x = (n c - (nc))/1) against y = D Pn where Pn is the probability of n charged particles being emitted (and E Pn = 1). The present data for K - p and 7r- p reactions are plotted in fig. 3 using the parameters of the x-y curve obtained by Czy2ewski and Rybicki from fitting the earlier data. It may be seen that a good fit is obtained.

5. Discussion of energy dependence The variation of the cross section for each charged multiplicity with x/s, where s is the square of the total c.m. energy, is given in figs. 4 and 5 for K - p and 7r- p reactions, respectively. It may be seen that the 2-prong inelastic and the 4-prong cross

83

V. V. A m m o s o v et al., K - p and 7r-p interactions I

1

1

I

1

1

I

i0 -I

i0-= ¢.1

EL II

I

i0-~ Tr-p 50 c,,v/¢

X2/N . 3.e/9

i~ K'p 33.86W/¢

I -2

I -I

XZ/N • 5,1/9

I

1

I

I

I

0

I

2

3

4

n¢ - (he> x=

D

Fig. 3. Comparison of 33.8 GeV/c K - p and 50 GeV/c n - p data with the Czy~ewski and Rybicki formula ref. [8]). sections both rise to a maximum value then decrease with increasing energy. The cross sections for the higher multiplicities are all still increasing. These results are consistent with those obtained from pp reactions studied in bubble chambers at Serpukhov and N.A.L. where it is found that the cross section for each charged multiplicity rises initially to a maximum and then decreases. The variation with energy o f the average charged multiplicity
V.V. A m m o s o v et al., K - p and ~r-p interactions

84

PLAB (GeVlc) 2

5

I0

20

30

40

I

i

I

I

i

I

K-p TOPOLOGICAL

CROSS SECTIONS

IoZ I this 2 prongs el. + ine4,

'°f

e,periment 1

aQ

E

g

iO-I

I--C) hi

l

iO-3

I

2

3

4

,5

6

7

8

9

I0

( GeV ) Fig. 4. Topological cross sections for K - p interactions as functions of the c.m. energy. The curves are hand drawn through the experimental points to guide the eye.

(n c) = a + b In (S/So),

(i)


(2)

where s o = 1 G e V 2, which are suggested by various models. No satisfactory fit could be o b t a i n e d w h e n the value f o u n d at 60 G e V / c in an emulsion e x p e r i m e n t was included and hence this point was excluded in subsequent fits.

85 '

'

I001-

I

'

I

7r'p

'

I

'

I

'

I

'

I

'

I

'

I

'

I

'I

t

TOPOLOGICAL CROSS SECTIONS

'~ IC

'~men

oo,,

,',,

3

5

7

9

(GeV) Fig. 5. Topological cross sections for 7r-p interactions as functions of the c.m. energy. The curves are hand drawn through the experimental points to guide the eye.

INCIDENT A

5 c l ~ I£~

v

-----=

~_

>-

LAB. I0 I



o

MOMENTUM , GeV/c 15 20 30 4 0 50 I I I I I

1.41 tn s/s o -- 0.62 1,40 (S/So)°'31

j

c-J

propane i

[ Tr-p

~; 5

w nI u

emulsion ~"

!hi, ~_~," experiment

-

4

I

I

I

I

I

I

I

4

5

6

7

8

9

I0

~ss,

(OeV)

Fig. 6. Average charged multiplicity in ~r-p reactions as a function of c.m. energy.

86

v.v. A m r n o s o v et aL, K p a n d ~ p i n t e r a c t i o n s

The values of the parameters found and the X2 - values divided by the number of degrees of freedom, are: a = -0.62 a =

+ 0.09,

b = 1.41 -+ 0 . 0 3 ,

1.40 + 0.03,

t3 = 0 . 3 1 -+ 0 . 0 1 ,

x2/N= 3 . 6 / 6 , x2/N= 8 . 5 / 6 .

These two fits are shown in fig. 6 as a dotted line for the log s fit and a solid line for the power of s. The log s fit has a better probability. When we compare the same plot for pp reactions, a similar curve is obtained, but displaced. We would n o w like to combine (n c) values for pp, lr p, 7r+p, K - p and K+p reactions in a universal plot. The average charged multiplicity (n c) has been plotted in fig. 7 against the Q-value of the reaction (defined as [ x / s - ( M h +MB)], where M A and M g are the mass of two incident particles) for pp, n p, zr+p, K p and K+p reactions. It may be seen that the values lie on a universal curve. This has been previously s h o w n by Wroblewski [9] for pp and ~ p reactions. One notices a tendency for the zr+ values to lie above the average.

i

A

g V

i

l-

-

l

~

T

~

- - -

aK + ,b'rr- ,K×p

I

077"*

-

/

/

I"---I 13..

I--__1

a hi

"r

w ne

W

1

2

i

l

I

I

5

I

I I [

I0

I

20

Q (GeV)

Fig. 7. Average charged multiplicity as a function of the Q-value for zr±p, K±p and pp reactions. The solid curve corresponds to a second-order polynomial fit to all data, except n+ values, with the expression ~nc) = 2.54 + 0.19 In Q + 0.59 (In Q)2

87

v. v. Ammosov et aL, K - p and 7r-p interactions

In table 3 are listed a compilation of values of (nc), D, (n c (n c - 1 ) ) , f2 and (nc)/D for 7t-+p, K+-p and pp reactions as functions of Q and of the incident momen-

tum. The quoted values and the errors have been recomputed in a standardized way for each experiment starting from the topological cross sections given by the authors or from the corresponding number of events. An important variable to study is the correlation integral f2 which can be determined from multiplicity distributions since f2 = (nc ( n c - - l ) ) - (nc)2" The interest o f f 2 is that its energy variation is different for different models, being log s in the multiperipheral model and s~ in diffraction models. In fig. 8 are shown the values o f f 2 plotted against the Q-value for zr-+p, K-*p and pp reactions. Except for a tendency for the 7r+ values to lie below the average, the values for the five reactions lie on a universal curve, thus again illustrating the advantages of plotting against the Q-values. I

•

I

I

i

07'/-+

n K*

*T/'-

A

i

i

i

i

~1

I

K-

/

xp

Io

f2 o

I

2

I

I

1

I

I I I

5

I

i

I0

20

Q (GeV)

Fig. 8. Plot of the correlation integral f2 as a function of the Q-value for rr+-p, K+-pand pp reactions. The solid curve corresponds to a third order polynomial fit to all data, except ~r+ values, with the expression ]'2 = - 1.81 + 0.55 In Q - 0.58 (In Q)2 + 0.52 (In 0 )

3 .

+

K-

7r

rr-

Incident particle

4.48

4.48

16.0

16.0

3.81

4.12

6.62

14.3

16.0

33.8

2.99

3.72

11.8

10.0

2.91

8.0

8.65

50.0

2.67

7.64

40.0

7.0

5.84

3.95

13.0

4.48

3.56

11.0

16.0

3.36

10.0

25.0

2.62

Q (GeV)

6.8

p (GeV/c)

5.16 +- 0.08

4.06 +- 0.04

3.83+-0.01

3.44+-0.03

4.51 +- 0.05

4.43 +- 0.14

4.07+-0.01

3.71+-0.02

3.64 +- 0.06

5.71 + 0.13

5.62 +- 0.04

4.85 +- 0.06

4 . 1 8 +- 0.05

3.99 +- 0.10

3.;4+-0.03

3.57 +- 0 . 0 2

3.15+-0.09

(nc>

C o m p i l a t i o n s o f ~,alues o f (nc>, D, (n c (nc-1)>, ./2 and r e a c t i o n is also given

Table 3

2.41 +- 0.03

1.84 +- 0.02

1.78±0.01

1.62+-0.02

1.80 +- 0.02

1.68 +- 0.08

1.63+-0.01

1.45.*0.01

1.40 +- 0.03

2.71 + 0.06

2.77 _4-0.04

2.11 +- 0.02

1.91 ± 0.04

1.78 ± 0.06

1.62+-0.03

1.67 +- 0.01

27.32 +- 0.64

15.77 +- 0.22

i3.96+-0.10

11.03-+0.15

19.08 +- 0.37

17.99 +- 1.07

15.17+-0.13

12.18+-0.13

11.57 +- 0.38

34.25 ~ 1.19

3 3 . 6 2 ± 0.55

23.15 +- 0.45

16.97 +- 0 . 3 2

12.84+-0.27

11.99 +- 0.13

(nc ( n c - 1 ) ~

-

-

-

-

-

-

-

-

-

-

-

-

-

f2

0 . 6 7 +- 0.19

0 . 6 8 +- 0 . 1 0

0.67+-0.04

0.83+-0.07

1.26 +- 0 . 1 2

1.59 +- 0.30

1.43+-0.04

1.61+-0.03

1.67 +- 0.10

1.,;5 + 0.36

2.03 +- 0.19

0.41 +- 0.14

0.53 ± 0 . 1 8

0 . 8 2 +- 0.15

1.12-'0.09

0 . 7 8 +- 0.04

1.25+-0.10

[13el

2.14 +- 0.04

2.21 +- 0.03

2.15±0.01

2.13+-0.03

2.50 +- 0.04

2.63 .* 0.14

2.50+-0.02

2.56+-0.02

2.60 +- 0.06

2.10 + 0 . 0 6

2.03 +- 0.03

[15a] this paper

[15b]

[15a]

[14c]

[14d]

[14c]

[14b]

[14a]

this paper

[13g]

[13f]

2.19 +- 0.05 2.30 ± 0.04

[13d]

[13cl

[13b]

[13a]

ref.

2.94 +- 0 . 0 9

2.31 +-0.05

2.14 +- 0 . 0 2

2.29±0.12

/D

zr+-p, K+-p a n d p p r e a c t i o n s at d i f f e r e n t i n c i d e n t m o m e n t a , p ; the Q-value o f the

1.38±0.06

D

/Dfor

I

I

7"

~.

~

~

~

~

"~

.~

O~

p

K+

Incident particle

3.38 +- 0.03

2.63

3.56

4.12

8.2

12.7

16.0

17.89

21.88

303.0

7.90

50.0

205.0

5.55

28.44

9.57

4.92

24.12

12.08

4.54

21.08

69.0

4.24

19.0

102.0

4.09

18.0

8.86 _+ 0.16

7.65 +- 0.17

6.34 -+ 0.14

5.89 +- 0.07

5.35-+0.11

4 . 3 3 +- 0 . 0 8

4.15+-0.07

4.02+-0.07

4.02 + 0.02

3.85 +- 0.07

3.57_+0.06

3.22 +- 0.05

2.66

3.22

10.0

2,76---0.01

4.17_+0.09

4.03+-0.12

1.62

12.88

5.5

2.94+-0.02

1.81

5.0

2.62_+0.02

1.35

3.5

2.57-+0.03



1.18

Q (GeV)

3~01

P (GeV]c)

Table 3 ( c o n l i n u e d ) 1)>

4.38 +- 0.10

3.89 +- 0.08

3.19 +- 0.08

2.89 -+ 0.03

2.57+-0.05

2.12 + 0.03

1.93+-0.02

1.89+-0.02

88.8

65.9

44.0

_+ 2.7

+- 2.2

_+ 1.6

37.14 +- 0 . 6 8

29.87_+0.95

18.86 +- 0.62

16.76+-0.53

15.74+-0.50

15.17 -+ 0.21

0.02

1.75 +

13.95 -+ 0.44

11.42_+0,37

8.91 +- 0.29

6.06+-0.07

16.23 + 0 . 7 2

14.60+-0.82

9.76 +- 0 . 1 9

6.90+-0.12

5.16-+0.09

4.86+-0.14


1.72 +- 0.02

1.50_+0.02

1.33 -+ 0.02

1.09+-0.01

1.74-+0.06

1.54-+0.05

1.32 +- 0.01

1.11 + 0 . 0 1

0.96-+0.01

0.91 +-0.01

D

-

-

-

-

-

-

-

-

-

-

-

f2

10.31 +- 0.92

7.44 + 0.72

3.88 +- 0.46

2.48 • 0.21

1.28+-0.27

0.15 +- 0.14

0.42+-0.12

0.44+0.11

0.96 -+ 0.06

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Wroblewski [10] has shown that there is an empirical relation between the dispersion, D, and (nc), namely D = A (n c) - B. Dao et al. [11] have studied, for pp reactions, the ratio (nc)/D and find that it decreases asymptotically with energy to the value 2. The ratio (nc)/D has been plotted in fig. 9a for n - p and K - p reactions and in fig. 9b for n+p, K+p and pp reactions. At low energies some differences can be observed caused by the difference in sign of the incident particle, e.g. zero-prong events can exist for n - p and K - p reactions but not when the two incident particles are positively charged. The general trend of the meson-proton reactions is similar to that observed for pp reactions. Using a two-component model Van Hove [12] has shown that the ratio (nc)/D should approach an asymptotic limit and the approach should be from above, as is observed in fig. 9. This work has been made possible through the constant support o f the USSR State Committee for Atomic Energy and the Commissariat h l'Energie Atomique and the Administration of the IHEP Protvino. We gratefully thank the constructors o f the IHEP beam No. 7, of the CERN fast ejection and R.F. separators and of the Saclay Mirabelle bubble chamber as well as all the accelerator staff and the operating crews whose cooperation has made possible a first run with a zr- beam in March 1972 and a K beam in June 1972.

K V. A m m o s o v et al., K - p and rr-p interactions

91

References [ 1 ] N. Galjaev, V. Kotov, A. Samoilov, V. Vaghin, P. Bernard, D. Lazard, P. Lazeyras, H. Lengeler, The high energy separated beam and the RF-separator for IHEP (Serpukhov), Proc. of the 7th Int. Conf. on high energy accelerators, Yerevan, August 1969, p. 531. [2] Yu. M. Antipov et al., Communication no. 105 presented at the 4th Int. Conf. on high energy collisions, Oxford, April 1972. [3] S.P. Denisov et al., Phys. Letters 36B (1971) 528. [4] A.P. Bugorski et al., Communication presented at the 16th Int. Conf. on high energy physics, Batavia, September 1972. [5] S. Brandt, Phys. Letters 32B (1970) 388. [6] ref. [17f, g, h]. [7] C.P. Wang, Phys. Rev. 180 (1969) 1463. [8] O. Czy£ewski, K. Rybicki, Nucl. Phys. B47 (1972) 633. [9] A. Wroblewski, High energy physics, Kiev Conf. report (1970) p. 42. [ 10] A. Wroblewski, Remarks on current models for charges multiplicity distributions, Warsaw preprint IFD/72/2 (1972). [11] F.T. Dao et al., Phys. Rev. Letters 29 (1972) 1627. [12] L. Van Hove, Phys. Letters, to be published and CERN preprint TH 1581 (1971). [ 13 ] n - p interactions: (a) 6.8 GeV/c: N.G. Birger et al., JINR preprint (1961) 789; the values in table 3 are taken from ref. [8]; (b) 10 GeV/c: J. Bartke, Nucl. Phys. 82 (1966)673; (c) 11 GeV/c: Genova - Hamburg - Milano - Saclay Collaboration; (d) 13 GeV/c: G.W. Brandenburg et al., Athens Conf., 1967: the values in table 3 are taken from ref. [8]; (e) 16 GeV/c: R. Honecker el al., Nucl. Phys. B13 (1969) 571; (f) 25 GeV/c: J.W. Elbert et al., Nucl. Phys. B19 (1970) 85; (g) 40 GeV/c: Bucharest-Budapest-Cracow-Dubna-Hanoi-Serpukhov-Sofia-Taskent-TbilisiUlan-Bator-Warsaw Collaboration, Phys. Letters B 39 ( 1972) 571. [ 14] n+p interactions: (a) 7.0 GeV/c: S.L. Stone et al., Nucl. Phys. B32 (1971) 19; (b) 8.0 GeV/c: M. Aderholz et al., Nucl. Phys. B8 (1968) 45; (c) 11.8 GeV/c : Durham-Genova-Hamburg-Milano-Saclay, private communication; (d) 16 GeV/c: J. Ballam et al., Phys. Rev. D3 (1971) 2606; (e) 16 GeV/c: ABBCCW Collaboration, CERN/HERA/72-1. [ 15] K - p interactions: (a) 10 and 16 GeV/c: Aachen-Bedin-CERN-London (IC)-Vienna Collaboration, private communication; (b) 14.3 GeV/c: Rutherford-Ecole Polytechnique-Saclay Collaboration, private communication. [ 16] K+p interactions: (a) 3.0, 3.5, 5.0 and 8.2 GeV/c: CERN-Brussels Collaboration, private communication; (b) 12.7 GeV/c: S.L. Stone et al., Nucl. Phys. B32 (1971) 19; (c) 16 GeV/c: Birmingham-Brussels-CERN-Mons-Paris-Saclay Collaboration, private communication. [ 17] pp interactions: (a) 5.5 GeV/c: G. Alexander et al., Phys. Rev. 154 (1967) 1284; (b) 10 GeV/c: S.P. Almeida et al., Phys. Rev. 174 (1968) 1638; (c) 12.88, 18.0, 21.08, 24.12 and 18.44 GeV/c: D.B. Smith, Berkeley report UCRL no. 20632 (1971);

92

K V. A m m o s o v et al., K - p and n - p interactions (d) 19 GeV/c: H. B~bggildet al., Nucl. Phys. B27 (1971) 285; (e) 50 and 69 GeV/c: Soviet-French Collaboration, Average charged particle multiplicity and topological cross sections in 50 GeV/c and 69 GeV/c pp interactions, 16th Int. Conf. on high energy physics, Batavia, September 1972; (f) 102 GeV/c: J.W. Chapman et al., Phys. Rev. Letters 29 (1972) 1686; (g) 205 GeV/c: G. Charlton et al., Phys. Rev. Letters 29 (1972) 515; (h) 303 GeV/c: F.T. Dao et al., Phys. Rev. Letters 29 (1972) 1627.