5 6 tZurze Or ig ina lmi t te i lungen. Die Natur- wissenschaften

I, ~43. -- STRUGHOLD, H. (1952): J. Aviation Med. ~ , 464. - - SZY~ANSKI, J. S. (19t8): Pfliigers Arch. 172, 430. - - TALbOt M. (t946): Ecology 2~, 65. - - TRES~SlIJS, J. (1931): Mitt. Vogelwelt ~0, 14, 35, 1 0 6 . - TRIBVXAI% B. (1953): Diss., zum Druck vor- gesehen. - - WaGXER, H. (t930): Z. vergl, Physiol. 12, 703. - - WARRZ~c,D.C., and H.M. Sco~w (1936): J. of Exp. Zool. 74,

1 3 7 . - W]EBB, .'VII. (1950): Physiol.-ZooI. 23, 316. ---WRIGHT, H. (19t3): Auk (Lancaster, Pa.) 30, 512.

Aus dem Max- Planck-fnstitut /fir Medizinische Forschung, Institut /iir Physiologic, Heidelberg.

Eingegangen am 26. Mai t953.

Kurze Originalmitteilungen. Pfir die K u r z e n Or ig ina lmi t t e i l ungen s ind aussch l ieg l ich die Ver fasse r ve r an twor t l i ch .

Symbols for fundamental particles. In recen t years we h a v e wi tnessed s t a r t l ing d e v e l o p m e n t s

in t he field of f u n d a m e n t a l par t ic les . One of t he consequences h a s been t he appea rance in t he scientif ic l i t e ra tu re of a new j a rgon and of a large n u m b e r of new symbols . Some s y m b o l s (such as ~, #, T) des igna te specific k inds of part icles . O the r s (such as ~, a) have been used to describe mere ly a pheno- menologicM behavior . Var ious a u t h o r s h a v e called t he s ame par t ic le b y di f ferent n a m e s or have a t t a c h e d dif ferent m e a n i n g to t he s a m e symbol . Some t imes t he m e a n i n g of a s y m b o l ha s c h a n g e d t h r o u g h t he years . To give an example , t he Greek le t te r ~ was used ini t ia l ly to describe a h e a v y m e s o n which s tops in t he emuls ion and s u b s e q u e n t l y decays g iv ing rise to a single ionizing part icle . L a t e r t he L a t i n le t t e r K replaced the Greek le t te r ~ as a code for t he above p h e n o m - enological descr ipt ion, while t he le t t e r z acqu i red a more defini te phys ica l m e a n i n g : t h a t of a h e a v y m e s o n which decays in to one charged and two neu t r a l part icles . S o m e t i m e s , however , t he le t te r K is also used to des igna te a n y cha rged par t ic le heav ie r t h a n a ~ - m e s o n and l igh ter t h a n a p ro ton , whose mode of decay is u n k n o w n . As a n o t h e r example , t he neu t r a l par t ic le of m a s s a b o u t t000 m e, which decays in to two ~-mesons , ha s been va r ious ly n a m e d v ~ V~ ~ Va~ whereas some a u t h o r s h a v e used t he le t t e r V ~ to des igna te a n y V ~ par t ic le di f ferent f rom t he so-called V~ ~ .

I t seems to us t ha t , in order to avoid confusion, t he t i m e ha s come to agree u p o n a co-ord ina t ion of t he symbo l s used to ind ica te f u n d a m e n t a l par t ic les or g roups of f u n d a m e n t a l par t ic les . Our specific sugges t ions are l is ted in t h e tab le to follow.

W e propose f irst to subd iv ide f u n d a m e n t a l par t ic les in to t h r ee groups according to the i r m a s s and to deno te each group b y a L a t i n let ter . W e t e n t a t i v e l y sugges t t he n a m e hyperon for a par t ic le of m a s s i n t e rmed i a t e be tween t h a t of t he n e u t r o n and t he deu te ron .

W e t h e n sugges t t h e use of Greek le t te rs to ind ica te specific par t ic les (as opposed to g roups of part icles) . W e no te t h a t th i s p rocedure h a s been widely followed in t he p a s t (recall t he symbo l s y, #, v, ~, z). W e do n o t propose, however , to change t he accepted s y m b o l s for the p ro t on (p) or t he neu- t r on (n).

We finally suggest to retain and make more precise the phenomenological classification already in use, based on the empirical features of the decay process (V-particles, S-part- icles).

C L A S S I F I C A T I O N OF P A R T I C L E S

A. Groups o/ParHdes.

Ligh t m e s o n s (L-mesons) : ~ -mesons , /z-mesons, a n y o ther l igh ter meson which m a y be discovered.

H e a v y mesons (K-mesons) : all par t ic les heav ie r t h a n :~-mesons and l ighter t h a n pro tons .

H y p e r o n s (Y-par t ic les) : all par t ic les wi th m a s s i n t e rmed ia t e be tween t h a t of t he n e u t r o n a n d t he deu te ron (this defini- t ion m i g h t be revised if f u n d a m e n t a l par t ic les heav ie r t h a n deu te rons are discovered).

B. " C h r i s t i a n Names".

Use capi ta l Greek le t te rs for h y p e r o n s a n d smal l Greek le t te rs for mesons .

1. Hyperom. A~ par t ic le p rev ious ly k n o w n as V1 ~ and charac te r ized by

the decay s chem e A ~ -~ p + ~ - . I f i t t u r n s ou t (as sugges ted b y some results) t h a t t he r e are par t ic les w i t h th i s decay

s cheme and d i f ferent Q-values, t h e y could be des igna ted by dif ferent subscr ip ts .

A+: t he posi t ive c o u n t e r p a r t of A ~ wi th the possible decay schemes :

A § -> n + ~+, A + _+ p + ~0.

The ex is tence of these par t ic les is ind ica ted b y recen t expe r imen t s .

2. Heavy Mesons. z - + 3 ~ (considered certain) .

~ # + 2 neu t r a l par t ic les (considered ve ry probable ; however t he n a t u r e of t he neu t r a l p roduc t s is still unkown) .

Z -~ ~ + t neu t r a l par t ic le (considered as p robab le ; n a t u r e of neu t r a l par t ic le unknown) .

0~ part ic le p rev ious ly k n o w n as v ~ l/~ ~ V~ o, charac te r ized b y t he decay scheme 00-+~ • ( ~ or l,~). If i t t u r n s o u t (as sugges t ed b y some resul ts) t h a t the re are par t ic les w i th th is decay scheme and severa l Q-values, t h e y could be des igna ted by dif ferent subcr ip t s .

C. Pheno~nenologieal Categories

V-even t : p h e n o m e n o n which can be in t e rp re t ed as t h e decay in f l ight of K - m e s o n or Y-part icle . Subdiv is ions : V~ decay of a neu t r a l par t ic le ; V+-event , decay of a cha rged par t ic le .

S -even t : p h e n o m e n o n which can he in t e rp re t ed as t he decay a t res t of a cha rged K-par t i c l e or Y-part icle .

E. AMALDI, ]{oma. C. D. ANDERSON, P a s a d e n a (California). P. M. S. BLACKETT, London . W. B. F~ETT~R, Berke ley 4 (California). L. LEPRINCE-RINGUET, Par is . B. P~TE~S, B o m b a y . C. F. POWELI~, Bristol . C. D. ROCI~ESrER, Manches te r . B. Ross I , Cambr idge (Mass.). R. Xu THOMPSON B l o o m i n g t o n ( Indiana) .

Eingegangen am 16. Dezember t953.

Zur elastischen Streuung yon positiv und negativ geladenen [x-Mesonen an schweren Kernen.

Von den beiden wich t igs t en Ar ten yon Mesonen (~,/~) zeigen bekann t l i ch die /~-Mesonen eine sehr s chwache Ko p p - lung an das Kernfe ld , so dug ihre Wechse lw i rkung mi t A t o m - ke rnen we i tgehend auf G r u n d der e l ek t romagne t i s chen K o p p - lung allein beschr ieben werden kann . Somi t s ind die #-Me- sonen eine geeignete Sonde, u m die P r o t o n e n v e r t e i l u n g im Kern n n d ghnliche, re in e lek t ros ta t i sche F ragen zu un te r - snchen . Die b isher a l l e i n erfolgte B e h a n d l u n g gebu~cde~zer Zus tgnde 1) (mesic a toms) h a t dabei einige U n k l a r h e i t e n hervor - gerufen [scheinbar zu Meine Rad i en der Pro tonenkugel~)] . In u n s e r e m I n s t i t u t wurde desha lb begonnen , die Streuung yon # -Mesonen an A t o m k e r n e n theore t i sch zn behande ln , die im Z u s a m m e n h a n g mi t expe r imen te l l en U n t e r s u c h u n g e n nenes Mater ia l zu d e m g e n a n n t e n Prob lemkre i s liefern kann . Der folgende Ber ich t en thg l t die ers ten Ergebnisse , die an andere r Stelle ausf i ihr l ich publ iz ier t we rden sollen.

Die K o p p l n n g der # -Mesonen an den A t o m k e r n e n geschieht fiber das CouLoMB-Potent ial , das ins I i e rn inne re als Parabe l - po ten t ia l for tgese tz t ist, wobei l e t z t e rem die V o r a u s s e t z u n g des h o m o g e n ge ladenen Ke rns z u g r u n d e liegt. Die Fig. 1 a und I b zeigen die Energ ieve rhg l tn i s se f t i r /~-Mesonen beiderlei Vorzeichens. Bet e iner E rn i ed r igung der k ine t i schen Mesonen-