39:
20:
884:
Sótér, Anna; Aghai-Khozani, Hossein; Barna, Dániel; Dax, Andreas; Venturelli, Luca; Hori, Masaki; Hayano, Ryugo; Friedreich, Susanne; Juhász, Bertalan; Pask, Thomas; Horváth, Dezső; Widmann, Eberhard; Venturelli, Luca; Zurlo, Nicola (2011-07-27). "Two-photon laser spectroscopy of antiprotonic helium
802:
helium by spectroscopic measurements, the first time on an exotic atom containing a meson. Its existence had been predicted in 1964 by George Condo at
University of Tennessee to explain some anomalies from bubble chamber tracks but no definite proof of its existence had ever been obtained. In the
663:
He and rapid annihilation produced a detectable Čerenkov signal. The reduced
Doppler shift resulted in narrower spectral lines accurate to between 2.3 and 5 ppb. Comparison of the results with three-body quantum electrodynamics calculations made possible a determination of the antiproton to
807:
were magnetically focused into a tank filled with superfluid helium so that they would expel an electron from the atom and take its place. Later, to confirm the production, laser light was fired at various frequencies until they found a specific one at 1631 nm where the pion would resonate
347:
can be produced by simply mixing antiprotons with ordinary helium gas; the antiproton spontaneously displaces one of the two electrons contained in a normal helium atom in a chemical reaction, and then begins to orbit the helium nucleus in the electron's place. This will happen in the case of
405:
As in spectroscopy of other bound states, Doppler broadening and other effects present challenges to precision. Researchers use a variety of techniques to obtain accurate results. One way to exceed
Doppler-limited precision is two-photon spectroscopy. The ASACUSA Collaboration has studied
38:
812:
from its orbit into an inner one and eventually into the nucleus which would break down into a proton, a neutron and a deuteron. The experiment proved highly technical to perform and took 8 years, including the design and construction of the experiment.
402:. In these experiments, the atoms are first produced by stopping a beam of antiprotons in helium gas. The atoms are then irradiated by powerful laser beams, which cause the antiprotons in them to resonate and jump from one atomic orbit to another.
763:
of the antiproton can be precisely compared with the proton values. The most recent such measurements show that the antiproton's mass (and the absolute value of the charge) is the same as the proton's to a precision of 0.5 parts in a billion.
507:
38 using 2-photon spectroscopy. Counterpropagating Ti:Sapphire lasers with pulses of duration 30−100 ns excited nonlinear 2-photon transitions in the deep UV, including spectral lines of wavelengths,
590:
356:
of around 38, lies far away from the surface of the helium nucleus. The antiproton can thus orbit the nucleus for tens of microseconds, before finally falling to its surface and
505:
715:. This is the same as the mass of a "regular" proton, within the level of certainty of the experiment. This is a confirmation of a fundamental symmetry of nature called
638:
528:
327:. It is thus made partly of matter, and partly of antimatter. The atom is electrically neutral, since an electron and an antiproton each have a charge of −1
1166:
1003:
162:
719:(short for charge, parity, and time reversal). This law says that all physical laws would remain unchanged under simultaneous reversal of the
296:
743:
By comparing the above results on laser spectroscopy of antiprotonic helium with separate high-precision measurements of the antiproton's
1052:
Hori, M.; et al. (2016). "Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio".
854:
353:
200:
1027:
225:
1217:
776:
is a two-body object composed of a helium nucleus and orbiting antiproton. It has an electric charge of +1
533:
938:
Sótér, Anna; Aghai-Khozani, Hossein; Barna, Dániel; Dax, Andreas; Venturelli, Luca; Hori, Masaki (2022-03-16).
349:
289:
348:
approximately 3% of the antiprotons introduced to the helium gas. The antiproton's orbit, which has a large
1237:
795:
195:
1242:
89:
1116:
1061:
951:
190:
475:
1232:
282:
253:
1148:
1085:
920:
894:
780:. Cold ions with lifetimes of up to 100 ns were produced by the ASACUSA experiment in 2005.
680:
530:
139.8, 193.0 and 197.0 nm. These lines correspond to transitions between states of the form
599:
510:
1140:
1132:
1077:
985:
967:
912:
235:
167:
1103:
Hori, Masaki; Aghai-Khozani, Hossein; Sótér, Anna; Dax, Andreas; Barna, Daniel (6 May 2020).
1124:
1069:
975:
959:
904:
724:
335:. It has the longest lifetime of any experimentally produced matter–antimatter bound state.
152:
147:
847:
1247:
1167:"ASACUSA sees surprising behaviour of hybrid matter–antimatter atoms in superfluid helium"
1004:"ASACUSA sees surprising behaviour of hybrid matter–antimatter atoms in superfluid helium"
789:
760:
752:
720:
263:
1120:
1065:
955:
592:. Such transitions are improbable. However, the probability is increased by a factor of
980:
939:
324:
1226:
1152:
732:
185:
1104:
1089:
924:
809:
716:
357:
207:
157:
142:
137:
104:
70:
48:
472:
occupying a high
Rydberg state with large principal and orbital quantum numbers,
822:
344:
114:
65:
963:
1190:
1128:
596:
when the laser frequencies sum to within 10 GHz of an intermediate state
313:
258:
230:
119:
75:
60:
30:
19:
1136:
971:
1073:
827:
804:
744:
692:
1144:
1081:
989:
940:"High-resolution laser resonances of antiprotonic helium in superfluid 4He"
916:
731:
axis. One important prediction of this theory is that particles and their
712:
699:
experiment determined the mass of the antiproton, which they measured at
317:
55:
908:
696:
395:
109:
99:
321:
899:
748:
82:
18:
687:
Measurement of the mass ratio between the antiproton and electron
799:
756:
728:
399:
268:
360:. This contrasts with other types of exotic atoms of the form
683:
unexpected narrowing of antiprotonic helium spectral lines.
640:. States were selected pairwise such that Auger emission to
879:
877:
875:
16:
Exotic matter with an antiproton in place of an electron
739:
Comparison of antiproton and proton masses and charges
798:
reported the experimental verification of long lived
602:
536:
513:
478:
695:
of the laser light needed to resonate the atom, the
848:"PROGRESS REPORT OF THE ASACUSA AD-3 COLLABORATION"
331:, whereas a helium nucleus has a charge of +2
632:
584:
522:
499:
394:Antiprotonic helium atoms are under study by the
23:Schematic drawing of an antiprotonic helium atom.
1028:"Icy Antimatter Experiment Surprises Physicists"
803:experiment negatively charged pions from a ring
1218:ASACUSA improves measurement of antiproton mass
290:
8:
885:and the antiproton-to-electron mass ratio".
386:, which typically decay within picoseconds.
1105:"Laser spectroscopy of pionic helium atoms"
794:In 2020 ASACUSA in collaboration with the
585:{\displaystyle (n,l)\rightarrow (n-2,l-2)}
297:
283:
26:
979:
898:
601:
535:
512:
477:
839:
29:
7:
312:is a three-body atom composed of an
735:should have exactly the same mass.
14:
860:from the original on 7 July 2022
37:
354:angular momentum quantum number
201:Relativistic Heavy Ion Collider
627:
603:
579:
555:
552:
549:
537:
500:{\displaystyle n\sim l+1\sim }
1:
747:frequency carried out by the
727:, and the orientation of the
796:Paul Scherrer Institut (PSI)
755:collaborations at CERN, the
691:By measuring the particular
226:Positron emission tomography
711:times more massive than an
1264:
964:10.1038/s41586-022-04440-7
787:
1129:10.1038/s41586-020-2240-x
633:{\displaystyle (n-1,l-1)}
523:{\displaystyle \lambda =}
163:Gravitational interaction
768:Antiprotonic helium ions
725:parity of the space axes
350:principal quantum number
1074:10.1126/science.aaf6702
774:antiprotonic helium ion
664:electron mass ratio of
634:
586:
524:
501:
196:Antiproton decelerator
132:Concepts and phenomena
24:
635:
587:
525:
502:
90:Antiprotonic hydrogen
22:
600:
534:
511:
476:
191:Particle accelerator
1121:2020Natur.581...37H
1066:2016Sci...354..610H
956:2022Natur.603..411S
909:10.1038/nature10260
310:Antiprotonic helium
254:Carl David Anderson
95:Antiprotonic helium
630:
582:
520:
497:
452:He atoms with the
390:Laser spectroscopy
320:orbiting around a
25:
950:(7901): 411–415.
893:(7357): 484–488.
307:
306:
168:Positron emission
1255:
1205:
1204:
1202:
1201:
1187:
1181:
1180:
1178:
1177:
1163:
1157:
1156:
1100:
1094:
1093:
1049:
1043:
1042:
1040:
1039:
1024:
1018:
1017:
1015:
1014:
1000:
994:
993:
983:
935:
929:
928:
902:
881:
870:
869:
867:
865:
859:
852:
844:
710:
708:
704:
679:In 2022 ASACUSA
675:
673:
669:
662:
659:
658:
657:
651:
648:
647:
639:
637:
636:
631:
595:
591:
589:
588:
583:
529:
527:
526:
521:
506:
504:
503:
498:
471:
470:
469:
463:
460:
459:
451:
448:
447:
446:
440:
437:
436:
428:
425:
424:
423:
417:
414:
413:
382:
379:
378:
377:
371:
368:
367:
299:
292:
285:
148:Baryon asymmetry
41:
27:
1263:
1262:
1258:
1257:
1256:
1254:
1253:
1252:
1223:
1222:
1214:
1212:Further reading
1209:
1208:
1199:
1197:
1191:"Pionic helium"
1189:
1188:
1184:
1175:
1173:
1165:
1164:
1160:
1115:(7806): 37–41.
1102:
1101:
1097:
1060:(6312): 610–4.
1051:
1050:
1046:
1037:
1035:
1032:Quanta Magazine
1026:
1025:
1021:
1012:
1010:
1002:
1001:
997:
937:
936:
932:
883:
882:
873:
863:
861:
857:
850:
846:
845:
841:
836:
819:
792:
790:Kaonic hydrogen
786:
770:
761:electric charge
741:
706:
702:
700:
689:
671:
667:
665:
660:
656:
654:
653:
652:
649:
646:
644:
643:
642:
641:
598:
597:
593:
532:
531:
509:
508:
474:
473:
468:
466:
465:
464:
461:
458:
456:
455:
454:
453:
449:
445:
443:
442:
441:
438:
435:
433:
432:
431:
430:
426:
422:
420:
419:
418:
415:
412:
410:
409:
408:
407:
392:
380:
376:
374:
373:
372:
369:
366:
364:
363:
362:
361:
341:
303:
274:
273:
264:Andrei Sakharov
249:
241:
240:
221:
213:
212:
181:
173:
172:
133:
125:
124:
51:
17:
12:
11:
5:
1261:
1259:
1251:
1250:
1245:
1240:
1238:Atomic physics
1235:
1225:
1224:
1221:
1220:
1213:
1210:
1207:
1206:
1195:www.mpq.mpg.de
1182:
1158:
1095:
1044:
1019:
995:
930:
871:
838:
837:
835:
832:
831:
830:
825:
818:
815:
785:
782:
769:
766:
740:
737:
688:
685:
655:
645:
629:
626:
623:
620:
617:
614:
611:
608:
605:
581:
578:
575:
572:
569:
566:
563:
560:
557:
554:
551:
548:
545:
542:
539:
519:
516:
496:
493:
490:
487:
484:
481:
467:
457:
444:
434:
421:
411:
398:experiment at
391:
388:
375:
365:
340:
337:
305:
304:
302:
301:
294:
287:
279:
276:
275:
272:
271:
266:
261:
256:
250:
247:
246:
243:
242:
239:
238:
233:
228:
222:
219:
218:
215:
214:
211:
210:
205:
204:
203:
198:
188:
182:
179:
178:
175:
174:
171:
170:
165:
160:
155:
150:
145:
140:
134:
131:
130:
127:
126:
123:
122:
117:
112:
107:
102:
97:
92:
79:
78:
73:
68:
63:
58:
52:
47:
46:
43:
42:
34:
33:
15:
13:
10:
9:
6:
4:
3:
2:
1260:
1249:
1246:
1244:
1241:
1239:
1236:
1234:
1231:
1230:
1228:
1219:
1216:
1215:
1211:
1196:
1192:
1186:
1183:
1172:
1168:
1162:
1159:
1154:
1150:
1146:
1142:
1138:
1134:
1130:
1126:
1122:
1118:
1114:
1110:
1106:
1099:
1096:
1091:
1087:
1083:
1079:
1075:
1071:
1067:
1063:
1059:
1055:
1048:
1045:
1033:
1029:
1023:
1020:
1009:
1005:
999:
996:
991:
987:
982:
977:
973:
969:
965:
961:
957:
953:
949:
945:
941:
934:
931:
926:
922:
918:
914:
910:
906:
901:
896:
892:
888:
880:
878:
876:
872:
856:
849:
843:
840:
833:
829:
826:
824:
821:
820:
816:
814:
811:
808:undergoing a
806:
801:
797:
791:
784:Pionic helium
783:
781:
779:
775:
767:
765:
762:
758:
754:
750:
746:
738:
736:
734:
733:antiparticles
730:
726:
722:
718:
714:
698:
694:
686:
684:
682:
677:
624:
621:
618:
615:
612:
609:
606:
576:
573:
570:
567:
564:
561:
558:
546:
543:
540:
517:
514:
494:
491:
488:
485:
482:
479:
403:
401:
397:
389:
387:
385:
359:
355:
351:
346:
338:
336:
334:
330:
326:
323:
319:
315:
311:
300:
295:
293:
288:
286:
281:
280:
278:
277:
270:
267:
265:
262:
260:
257:
255:
252:
251:
245:
244:
237:
234:
232:
229:
227:
224:
223:
217:
216:
209:
206:
202:
199:
197:
194:
193:
192:
189:
187:
186:Cloud chamber
184:
183:
177:
176:
169:
166:
164:
161:
159:
156:
154:
151:
149:
146:
144:
141:
139:
136:
135:
129:
128:
121:
118:
116:
113:
111:
108:
106:
103:
101:
98:
96:
93:
91:
88:
87:
86:
85:
84:
77:
74:
72:
69:
67:
64:
62:
59:
57:
54:
53:
50:
49:Antiparticles
45:
44:
40:
36:
35:
32:
28:
21:
1243:Exotic atoms
1198:. Retrieved
1194:
1185:
1174:. Retrieved
1170:
1161:
1112:
1108:
1098:
1057:
1053:
1047:
1036:. Retrieved
1034:. 2022-03-16
1031:
1022:
1011:. Retrieved
1007:
998:
947:
943:
933:
890:
886:
862:. Retrieved
842:
810:quantum jump
793:
777:
773:
771:
742:
690:
678:
404:
393:
383:
358:annihilating
345:exotic atoms
342:
332:
328:
309:
308:
208:Penning trap
158:CP violation
143:Baryogenesis
138:Annihilation
105:True muonium
94:
81:
80:
71:Antihydrogen
823:Positronium
115:Positronium
66:Antineutron
1233:Antimatter
1227:Categories
1200:2022-03-16
1176:2022-03-16
1038:2022-03-17
1013:2022-03-17
834:References
788:See also:
339:Production
314:antiproton
259:Paul Dirac
248:Scientists
120:Quarkonium
76:Antihelium
61:Antiproton
31:Antimatter
1153:218527999
1137:1476-4687
972:1476-4687
900:1304.4330
828:Protonium
805:cyclotron
745:cyclotron
693:frequency
622:−
610:−
574:−
562:−
553:→
515:λ
495:∼
483:∼
1145:32376962
1090:37796298
1082:27811273
990:35296843
917:21796208
855:Archived
817:See also
713:electron
318:electron
56:Positron
1117:Bibcode
1062:Bibcode
1054:Science
981:8930758
952:Bibcode
925:4376768
864:30 July
697:ASACUSA
661:
450:
429:He and
427:
396:ASACUSA
381:
325:nucleus
316:and an
180:Devices
110:Pionium
100:Muonium
1248:Helium
1151:
1143:
1135:
1109:Nature
1088:
1080:
988:
978:
970:
944:Nature
923:
915:
887:Nature
800:pionic
723:axis,
721:charge
343:These
322:helium
236:Weapon
1149:S2CID
1086:S2CID
921:S2CID
895:arXiv
858:(PDF)
851:(PDF)
749:ATRAP
681:found
153:Comet
1171:CERN
1141:PMID
1133:ISSN
1078:PMID
1008:CERN
986:PMID
968:ISSN
913:PMID
866:2022
759:and
757:mass
753:BASE
751:and
729:time
709:(15)
707:6734
705:.153
674:(23)
672:6736
670:.152
400:CERN
352:and
269:CERN
231:Fuel
220:Uses
83:Onia
1125:doi
1113:581
1070:doi
1058:354
976:PMC
960:doi
948:603
905:doi
891:475
772:An
717:CPT
703:836
668:836
1229::
1193:.
1169:.
1147:.
1139:.
1131:.
1123:.
1111:.
1107:.
1084:.
1076:.
1068:.
1056:.
1030:.
1006:.
984:.
974:.
966:.
958:.
946:.
942:.
919:.
911:.
903:.
889:.
874:^
853:.
676:.
594:10
1203:.
1179:.
1155:.
1127::
1119::
1092:.
1072::
1064::
1041:.
1016:.
992:.
962::
954::
927:.
907::
897::
868:.
778:e
701:1
666:1
650:p
628:)
625:1
619:l
616:,
613:1
607:n
604:(
580:)
577:2
571:l
568:,
565:2
559:n
556:(
550:)
547:l
544:,
541:n
538:(
518:=
492:1
489:+
486:l
480:n
462:p
439:p
416:p
384:X
370:p
333:e
329:e
298:e
291:t
284:v
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
